GIFT   OF 
Samuel   G.   Clark 


EARTH 

SCIENCES 

LIBRARY 


'i    . 


OF 


DETERMINATIVE    MINERALOGY 

WITH  AN   INTRODUCTION  ON 

BLOWPIPE    ANALYSIS. 


BY 


GEORGE  J.   BRUSH, 

Late  Director  of  the  Sheffield  Scientific  School  of  Yale  University, 


REVISED  AND   ENLARGED,  WITH  ENTIRELY  NEW   TABLES 
FOR  THE  IDENTIFICATION  OF  MINERALS, 

BY 

SAMUEL   L.  PENFIELD, 

Late  Professor  of  Mineralogy  in  the  Sheffield  Scientific  School 
of  Yale  University. 


SIXTEENTH    EDITION,    REVISED. 
TOTAL   ISSUE,    TWELVE    THOUSAND 


NEW   YORK 

JOHN  WILEY  &   SONS,  INC. 
LONDON:   CHAPMAN  &  HALL,  LIMITED 
1914 


EARTH 

SCIENCES 
LIBRARY 


COPYRIGHT,  1898, 

BY 

SAMUEL  L.  PENFIELD. 


GPOLOGICAL  SCIENCES 


THE   SCIENTIFIC    PRESS 
ERT    DRUMMOND    AND    COMPANY 
BROOKLYN,    N.    Y. 


PREFACE. 


THE  present  work  is  a  complete  revision  of  the  "  Manual  of 
Determinative  Mineralogy  and  Blowpipe  Analysis"  by  Prof.  Geo. 
J.  Brush,  which  has  been  very  generally  used  since  its  first  appear- 
ance in  1874,  as  shown  by  the  fact  that  fourteen  editions  of  it  have 
appeared.  In  1896  a  revision  of  the  introductory  chapters  devoted 
to  blowpipe  analysis  and  the  chemical  reactions  of  the  elements 
was  published,  and  there  are  now  added  a  chapter  on  the  physical 
properties  of  minerals,  devoted  chiefly  to  crystallography,  and  a 
new  set  of  analytical  tables  for  the  identification  of  minerals. 

In  preparing  the  introductory  chapters,  great  pains  has  been 
taken  in  the  selection  of  the  tests  for  the  elements.  Many  of  the 
experiments  are  performed  by  means  of  the  blowpipe,  but  chem- 
ical tests  in  the  wet  way  are  recommended  when  it  is  believed  that 
they  are  more  decisive.  All  the  tests  have  been  carefully  verified, 
and  many  of  them  have  been  devised  especially  for  the  present 
work.  To  make  the  book  more  convenient  for  reference,  conspic- 
uous headlines  and  catch-words  have  been  freely  used.  The  tests 
for  the  rare  elements,  and  those  for  the  common  ones  which  are 
only  occasionally  employed,  are  printed  in  small  type.  It  is  hoped 
that  the  plan  adopted  of  giving  full  directions  concerning  the 
methods  of  manipulation  and  the  quantities  of  materials  to  be 
taken  in  making  many  of  the  tests  will  be  found  useful. 

It  must  be  borne  in  mind  constantly  that  accuracy  is  of  the 
utmost  importance  in  determinative  mineralogy,  and  it  is  believed 
that  no  methods  are  so  generally  to  be  relied  upon  for  giving  deci- 
sive results  as  those  based  upon  the  identification  of  the  chemical 
constituents  of  the  minerals.  Moreover,  most  minerals  can  be  iden- 
tified by  means  of  very  simple  tests,  although  some  cannot  be 
determined  beyond  question  without  resorting  to  the  more  elab- 

iii 

GB55794 


IV  PREFACE. 

orate  methods  of  quantitative  chemical  analysis,  or  an  exact  deter- 
mination of  their  crystalline  form. 

The  chapter  on  the  physical  properties  of  minerals  is  a  new 
feature  of  the  book  which  it  is  believed  will  add  to  its  usefulness. 
The  endeavor  has  been  made  to  present  the  important  subject  of 
crystallography  as  simply  as  possible.  Importance  has  been 
attached  to  the  description  of  those  forms  which  are  most  frequent 
in  their  occurrence,  and,  with  few  exceptions,  the  examples  chosen 
to  illustrate  the  different  systems  represent  the  development  of  the 
simple  forms  which  prevail  on  specimens  of  common  minerals. 
Hare  and  complex  forms  have  been  treated  very  briefly,  and  theo- 
retical considerations  have  been  left  largely  to  the  more  elaborate 
treatises  on  crystallography.  In  describing  the  physical  properties 
of  crystals  the  idea  has  constantly  been  kept  in  mind  that  the  book 
is  to  be  used  for  the  identification  of  minerals,  and,  consequently, 
only  those  methods  are  included  which  are  especially  important  as 
a  means  for  identification.  Optical  methods  have  been  omitted 
because  they  would  increase  the  size  of  the  volume  to  too  great  an 
extent,  and,  except  as  they  are  accompanied  by  accurate  descrip- 
tions of  the  crystal  forms,  their  application  is  limited. 

The  analytical  tables  for  the  identification  of  minerals  are  an 
outgrowth  of  the  tables  of  von  Kobell  as  modified  by  Professor 
Brush.  The  introduction,  however,  of  a  large  number  of  new 
species  since  1874  has  necessitated  a  complete  rearrangement  of 
the  minerals.  The  tables  have  been  so  developed  that  tests  for 
characteristic  chemical  constituents  furnish  the  chief  means  for 
identification.  Thus,  in  identifying  minerals,  students  may  gain 
possession  of  important  information  concerning  the  chemical  com- 
position of  the  compounds.  The  distribution  of  the  minerals  in  the 
tables,  and  statements  concerning  their  chemical  and  blowpipe 
characters,  have  been  verified  in  almost  all  cases  by  experiments 
made  upon  well-authenticated  specimens  in  the  Brush  collection  at 
New  Haven.  In  some  cases,  however,  it  has  not  been  possible  to 
locate  rare  minerals  with  certainty  in  the  places  where  they  prop- 
erly belong,  because  the  original  descriptions  have  not  been  suffi- 
ciently complete.  The  author  would  be  pleased  to  receive  any 
information  concerning  the  properties  of  minerals  which  could  be 
incorporated  in  future  editions,  and  thus  render  the  tables  more 
complete  and  accurate.  The  tables  are  intended  to  include  all  of 
the  well-characterized  mineral  species  known  at  the  present  time, 
and  although  nearly  eight  hundred  species  have  been  included,  it  is 


PREFACE.  V 

believed  that  they  are  adapted  to  the  use  of  beginners  who  desire 
especially  to  become  acquainted  with  the  common  minerals.  In 
order  to  accomplish  this  end  the  common  minerals  are  printed 
conspicuously  in  capitals,  and  thus  on  opening  any  page  of  the 
tables  they  may  be  recognized  at  once  by  glancing  down  the 
column  "  Name  of  Species." 

The  author  takes  pleasure  in  expressing  his  obligations  to  his 
associates,  Professors  G.  J.  Brush,  E.  S.  Dana,  L.  V.  Pirsson,  and 
H.  L.  Wells,  for  many  valuable  suggestions,  and  to  the  Misses  L. 
P.  and  K.  J.  Bush  of  New  Haven  for  services  rendered  in  the 
preparation  of  the  manuscript  and  in  proof-reading.  The  wood- 
cuts were  prepared  by  the  skillful  engraver,  Mr.  W.  F.  Hopson  of 
New  Haven. 

NEW  HAVEN,  October  1,  1898. 


PREFACES    OF   THE    FORMER 

EDITIONS  OF  THIS  WORK, 

BY  GEORGE  J.  BRUSH. 


PREFACE  TO  THE  FIRST  EDITION. 


THE  material  in  this  compilation  was,  far  the  greater  part, 
prepared  almost  twenty  years  since,  by  Prof.  S.  W.  Johnson 
and  myself,  as  a  text-book  for  the  students  in  our  laboratory. 
Circumstances  prevented  its  publication  at  that  time,  but  it  has 
served  as  the  basis  of  a  course  of  lectures  and  practical  exercises 
annually  given  in  the  Sheffield  Laboratory. 

The  plan  of  instruction  has  been  to  have  the  student  work 
through  a  course  of  Qualitative  Blowpipe  Analysis  as  introduc- 
tory to  Determinative  Mineralogy.  For  the  latter  subject,  we 
have  employed  VON  KOBELL'S  Tafeln  zur  Bestimmung  der  Mine- 
ralien,  many  of  the  students  taking  the  work  in  the  original, 
while  others  made  use  of  either  Erni's  or  Elderhorst's  transla- 
tions. These  "  Tables  "  were  translated  by  Prof.  Johnson  and  my- 
self while  we  were  students  of  Prof,  von  Kobell  in  1853-4,  at 
Munich,  and  it  was  after  our  suggestion,  in  1860,  to  Prof.  Elder- 
horst,  that  he  introduced  von  Kobell's  "Tables"  into  the  second 
edition  of  his  "  Manual,"  although  he  did  not  avail  himself  of  our 
translation,  which  was  then  offered  to  him  for  that  purpose. 

T! 


PREFACE  TO   THE   FIRST  EDITION".  vii 

The  "  Tables "  as  now  presented  are  based  on  the  tenth 
German  edition  of  von  Kobell's  book.  Additions  of  new  species 
have  been  made,  and  in  many  cases,  fuller  details  are  given  in  re- 
gard to  old  species,  and  the  whole  material  has  been  thrown  into 
an  entirely  new  shape,  which  it  is  believed  will  greatly  facilitate 
the  work  of  the  student.  The  preparation  of  the  tables  in  this 
form,  the  idea  of  which  was  suggested  to  me  by  Prof.  W.  T. 
ROEPPER,  has  been  performed,  under  my  supervision,  by  my  as- 
sistant, Mr.  GEORGE  W.  HAWES,  who  has  also  aided  me  greatly  in 
revising  the  rest  of  the  work,  and  in  the  reading  of  the  proof- 
sheets. 

The  main  authorities  used  in  the  original  preparation  and 
later  revision  of  the  chapters  on  Blowpipe  Analysis  were  the 
works  of  BERZELIUS  and  PLATTNER.  The  third  and  fourth  edi- 
tions of  Plattner,  the  latter  edited  by  Prof.  RICHTER,  have  been 
chiefly  consulted.  The  complete  work  of  Plattner,  with  still  later 
additions  by  Prof.  Richter,  has  been  made  accessible  to  English- 
reading  students  through  an  excellent  translation  by  Prof.  H.  B. 
CORNWALL,  and  this  cannot  be  too  highly  commended  to  those 
who  desire  to  become  fully  acquainted  with  this  important  sub- 
ject. 

In  Determinative  Mineralogy,  besides  the  works  of  von 
Kobell,  free  use  has  been  made  of  the  treatises  of  NAUMANN  and 
DANA,  especially  of  the  pyrognostic  characters  contributed  by 
myself  to  the  latter  work.  This  constitutes,  in  accordance  with 
the  original  plan  of  Professor  Dana  and  myself,  the  Determina- 
tive Part  of  his  System  of  Mineralogy.  It  is  proposed  at  some 
future  time  to  add  to  the  volume  methods  for  the  determination 
of  minerals  by  their  physical  characters. 

In  conclusion,  I  take  great  pleasure  in  acknowledging  my  in- 
debtedness to  my  colleague,  Prof.  S.  W.  Johnson,  who  has  not 
only  generously  given  me  his  share  in  the  original  work,  but  ha$ 
constantly  aided  me  by  his  advice  in  the  revision  here  presented. 

SHEFFIELD  LABORATORY  OF  YALE  COLLEGE, 
HAVEN-  December  15,  1874. 


PREFACE  TO  THE  THIRD  AND  LATER  EDITIONS. 


THIS  edition  has  been  so  far  revised  as  to  substitute  for  the 
old  formulas  for  minerals,  those  based  upon  the  atomic  weights 
of  the  elements  adopted  by  the  so-called  new  chemistry.  The 
formulas  for  the  most  part  have  been  taken  from  Rammelsberg '$ 
Mineralchemie  (Leipzig,  1875),  and  are  made  to  correspond  as 
far  as  possible  with  those  given  in  Dr.  E.  8.  Dana's  Text -Book 
of  Mineralogy  (John  Wiley  &  Sons,  New  York,  1877). 

It  should  be  stated  here  that  as  the  main  object  of  this  book 
is  the  identification  of  mineral  species  by  a  method  largely  based 
on  the  blowpipe  characters  of  their  elemental  constituents,  this 
point  has  been  kept  in  view  in  writing  their  formulas.  Instead 
of  giving  a  symbol  for  a  group  of  elements,  as  is  usual  in  min- 
eralogical  treatises,  it  has  been  necessary  to  give  the  elements 
in  full,  and  in  some  instances,  for  want  of  space,  a  simple  list  of 
the  constituents  is  substituted  for  the  formulas.  This  has  also 
been  done  in  the  case  of  minerals  where  no  satisfactory  formulas 
have  been  deduced. 

It  has  not  been  thought  advisable  to  alter  the  old  common 
names  used  for  reagents  and  compounds,  since  the  book  is  in- 
tended not  only  for  students  in  colleges  and  schools,  but  for  all  the 
different  classes  of  persons  who  are  interested  in  the  study  of 
minerals. 

A  few  changes  and  additions  in  the  text  of  the  tables  are 
made,  which,  it  is  trusted,  will  facilitate  the  work  of  the  student. 
My  acknowledgments  are  again  due  to  Mr.  George  W.  Hawes 
for  his  cooperation  in  making  these  changes. 

NEW  HAVEN,  May  1, 1878. 

viii 


TABLE  OF  CONTENTS. 


CHAPTER  I. 

PAOB 

INTRODUCTION  AND  CHEMICAL  PRINCIPLES. 

The  Mineral  Kingdom:  Minerals 1 

Rocks:   Chemistry 2 

CHAPTER  II. 

APPARATUS    AND    REAGENTS,    AND    CHEMICAL   PRINCIPLES   IN- 
VOLVED  IN  THEIR  USE. 

Apparatus 10 

Dry  Reagents 24 

Gaseous  Reagents  ;  Wet  Reagents 27 

The  Nature  and  Use  of  Flames 31 

CHAPTER  IIL 

REACTIONS  OF  THE  ELEMENTS. 

Aluminium • 42 

Other  Elements  follow  in  Alphabetical  Order. 

CHAPTER  IV. 

TABULATED  ARRANGEMENT  OF  THE  MORE  IMPORTANT  BLOWPIPE 
AND  CHEMICAL  REACTIONS. 

Heating  in  the  Platinum-pointed  Forceps  :  Flame  Coloration 135 

Heating  in  the  Closed  Tube 137 

Heating  in  the  Open  Tube 140 

Heating  on  Charcoal 142 

Treatment  with  Cobalt  Nitrate 146 

Fusion  with  the  Fluxes  on  Platinum  Wire 147 

Treatment  with  Acids,  and  Reactions  with  the  Common  Elements 151 

iz 


TABLE   OF   CONTENTS. 


CHAPTER  V. 

PAGB 

PHYSICAL  PROPERTIES  OF  MINERALS. 

Crystallography 155 

Structure  of  Minerals 221 

Cohesion  Relations  of  Minerals 223 

Properties  depending  upon  Light 227 

Properties  depending  upon  Heat 230 

Properties  depending  upon  Weight :  Specific  Gravity 232 


CHAPTER  VI. 

TABLES  FOR  THE  DETERMINATION  OF  MINERAL  SPECIES  BY  MEANS 
OF  SIMPLE  CHEMICAL  EXPERIMENTS  IN  THE  WET  AND  DRY 
WAY  AND  BY  THEIR  PHYSICAL  PROPERTIES. 

Introduction  to  the  Tables 239 

Analytical  Table  for  the  Identification  of  Minerals  :  General  Classification.. .  245 
Tables 246 

INDEX  TO  SUBJECT-MATTER 303 

INDEX  TO  MINERALS..  307 


DETEEMINATIVE  MINERALOGY  AND  BLOWPIPE 

ANALYSIS, 


CHAPTER  I. 

INTRODUCTION  AND   CHEMICAL  PRINCIPLES. 

The  Mineral  Kingdom.  —  Natural  products  are  commonly 
divided  into  three  kingdoms, — animal,  vegetable,  and  mineral. 
The  latter  includes  those  substances  constituting  or  found  in  the 
crust  of  the  earth  and  not  those  made  through  the  agency  of  life. 
They  are,  therefore,  frequently  called  inorganic  materials. 
Among  these,  two  classes  are  recognized,  which  are  known  as 
minerals  and  ?  ocTcs. 

Minerals.— These  are  definite  chemical  compounds  occurring 
in  the  mineral  kingdom.  The  following  may  serve  as  examples : 

Pyrite,  sulphide  of  iron,  FeS,. 

Quartz,  oxide  of  silicon,  SiO,. 

Orthoclase,  silicate  of  potassium  and  aluminium,  KAlSi,08. 

Chemical  formulae  show  the  invariable  composition  .of  the 
minerals  when  pure,  that  of  quartz,  for  example,  indicating  that 
1  atom  of  silicon  is  in  combination  with  2  atoms  of  oxygen.  It 
ought  to  be  possible  to  express  the  composition  of  every  mineral 
by  a  chemical  formula,  but  there  are  some  for  which  this  cannot 
yet  be  done,  owing  to  the  fact  that  they  have  not  been  sufficiently 
investigated. 

On  examining  minerals,  it  will  be  observed  that  they  usually 
occur  in  definite  geometrical  shapes  called  crystals,  when  condi- 
tions favorable  for  the  formation  of  crystals  have  prevailed. 


2  INTRODUCTION    AND   CHEMICAL    PRINCIPLES. 

Every  distinct  chemical  compound  occurring  in  inorganic  nature, 
having  a  definite  molecular  structure  or  system  of  crystallization 
and  well-defined  physical  properties,  constitutes  a  mineral  species. 
Up  to  the  present  time,  between  eight  and  nine  hundred  minerals, 
which  deserve  to  rank  as  distinct  species,  have  been  recognized. 
Of  these,  however,  only  a  few  can  be  considered  as  common,  and 
really  important  either  as  rock-forming  minerals  in  making  up  the 
crust  of  the  earth,  or  as  ores  of  the  useful  metals,  or  as  otherwise 
valuable  in  the  arts.  Each  mineral  species  has  received  a  name 
(usually  ending  in  ite,  signifying  ' of  the  nature  ofj  'UJce^  by 
which  it  is  commonly  known.  In  assigning  these  names  no  sys- 
tem has  been  followed,  some  being  derived  from  chemical,  phys- 
ical, or  fanciful  peculiarities,  some  from  localities  where  the 
minerals  were  first  found,  while  many  are  named  after  persons. 

Rocks. — With  the  exception  of  a  few  glassy  lavas,  rocks  are 
aggregates  of  mineral  particles.  The  term  rock  is  often  used  in  a 
general  way  for  designating  any  portion  of  the  earth's  crust,  but 
the  kinds  of  rock  to  which  geologists  have  assigned  special  names 
contain  certain  minerals  in  about  the  same  proportion  throughout. 
Thus,  granite  is  one  of  the  commonest  rocks  of  the  globe,  and,  on 
examination,  a  fragment  of  it  will  be  found  to  be  made  up  of 
different  minerals.  The  most  conspicuous  is  orthoclase,  KAlSi3Os, 
together  with  a  corresponding  soda  mineral,  albite,  NaAlSi9Op, 
and  quartz,  SiO,,  while  a  number  of  others  may  be  present  in 
small  amounts.  The  proportion  of  these  minerals  differs  in  differ- 
ent kinds  of  granite,  and  it  is  therefore  evident  that  the  composition 
of  this  rock  cannot  be  expressed  by  a  definite  chemical  formula. 

In  a  rock,  the  structure  may  be  coarse-grained,  so  that  the 
particles  can  be  detected  with  the  naked  eye,  or  fine-grained,  ren- 
dering a  microscope  necessary  to  distinguish  the  different  com- 
ponents. Usually  a  rock  is  composed  of  different  minerals,  but 
it  sometimes  consists  of  only  one.  Thus,  marble  is  an  aggregate 
of  particles  of  calcite,  CaCOs,  and  quartzite  of  quartz,  SiO,.  The 
study  of  rocks,  known  as  lithology  or  petrography,  necessitates  a 
previous  knowledge  of  mineralogy. 


INTRODUCTION  AND   CHEMICAL   PRINCIPLES.  3 

Chemistry. — Mineralogy  is  chiefly  a  chemical  science,  and  for  a 
proper  understanding  of  minerals,  some  knowledge  of  elementary 
chemistry  is  indispensable.  A  brief  summary,  therefore,  of  some 
important  chemical  principles  will  be  first  given.  By  a  careful 
study  of  the  experimental  part  of  the  following  chapters,  it  is 
believed  that  much  useful  information  concerning  general  element- 
ary chemistry  may  be  gained. 

Elements. — A  substance  which  cannot  be  separated  into  sim- 
pler constituents  is  regarded  as  an  element.  At  the  present  time, 
about  70  elements  are  recognized.  Of  these,  less  than  half  are 
of  common  occurrence,  while,  from  a  consideration  of  a  large  num- 
ber of  rock  analyses,  F.  W.  Clarke  *  has  calculated  that  99  per 
cent  of  the  solid  crust  of  the  earth,  for  a  depth  of  ten  miles,  is 
composed  of  the  following  eight  elements  : 

Oxygen,       47. 3#  Calcium,        3.8# 

Silicon,         27.2  Magnesium,  2.7 

Aluminium,  7.8  Sodium,         2.4 

Iron,  5.4  Potassium,    2.4 

Chemical  Affinity,  Atoms,  and  Molecules. — Elements  manifest 
tendencies  to  unite  with  one  another.  This  property  is  known  as 
chemical  affinity.  It  is  usually  strongest  between  metallic  and 
non-metallic  elements  ,  as  sodium  and  chlorine  in  sodium  chloride. 
The  smallest  particle  of  an  element  which  enters  into  combination 
is  called  an  atom,  and  the  smallest  particle  of  a  chemical  compound 
which  is  capable  of  existence  is  called  a  molecule. 

Symbols. — For  convenience,  elements  are  designated  by  sym- 
bols, usually  the  initial  letter  of  their  names,  or  this  with  one  other 
letter.  Each  symbol  stands  for  one  atom  of  the  element ;  as  S  for 
sulphur,  Pb  for  lead  (Latin,  plumbum).  PbS  is  the  chemical  for- 
mula of,  and  represents  a  molecule  of,  lead  sulphide. 

Law  of  Definite  Proportion. — Atoms  unite  with  one  another  in 
definite,  though  frequently  in  two  or  more  different,  proportions. 

*Phil.  Soc.  of  Washington,  Bull.  IX.,  p.  138,  1889. 


4  INTRODUCTION   AND    CHEMICAL   PRINCIPLES. 

For  example,  carbon,  sulphur,  and  arsenic,  each  form  two  distinct 
oxides,  CO  and  CO2,  SO,  and  SO,,  AsaO3  and  AsaO6. 

Valence. — This  term  is  used  to  express  the  numerical  propor- 
tion in  which  elements  unite  with  or  replace  hydrogen.  Chlorine 
is  univalent  and  oxygen  bivalent,  because  they  unite  with  hydro- 
gen to  form  the  molecules  HC1  and  HaO,  respectively.  The  term 
valence  is  also  applied  to  compounds.  Thus,  sulphuric  acid  being 
HaS04,  the  radical  S04  is  said  to  be  bivalent. 

Acids. — Compounds  resulting  from  the  union  of  non-metallic 
elements,  with  hydrogen  or  hydrogen  and  oxygen,  in  which 
the  hydrogen  atoms  may  be  replaced  by  metals,  are  called 
acids.  These  usually  possess  a  sharp,  sour  taste  and  have  the 
property  of  turning  blue  litmus-paper  red.  The  common  mineral- 
forming  acids  are  hydrochloric,  HC1 ;  nitric,  HN03 ;  hydrofluoric, 
HF ;  hydrogen  sulphide,  HaS  ;  sulphuric,  H2SO4 ;  carbonic,  H2CO3; 
boric,  H,B08;  phosphoric,  H3P04.;  arsenic,  H3As04;  orthosilicic, 
H4Si04 ;  metasilicic,  H4Sia06,  and  polysilicic,  H4SisO8.  In  the  fore- 
going formulae,  the  groups  of  elements  with  which  the  hydrogen 
atoms  are  united  are  often  called  acid  radicals.  Thus,  S04  is  the 
acid  radical  of  sulphuric  acid  ;  PO4  of  phosphoric  ;  Si04  of  ortho- 
silicic,  etc. 

Bases. — Combinations  of  metals  with  oxygen  and  hydrogen 
(the  hydroxides;  for  example,  NaOH,  sodium  hydroxide)  are 
called  bases.  .  These  have  the  property  of  neutralizing  acids,  and, 
if  soluble  in  water,  of  turning  red  litmus-paper  blue.  The 
combinations  of  metals  with  oxygen  are  sometimes  called  basic 
oxides. 

Salts.— Compounds  formed  by  the  combination  of  acids  and 
bases,  and  resulting  in  the  replacement  of  part  or  all  of  the  hydro- 
gen atoms  of  the  acid  by  metals,  are  called  salts.  The  great 
majority  of  minerals  are  salts,  and  in  a  natural  chemical  classifica- 
tion they  are  subdivided  into  groups  according  to  the  acid  radi- 
cals which  they  contain  ;  i.e.,  the  sulphides,  salts  of  hydrogen 
sulphide,  in  one  group ;  the  sulphates,  salts  of  sulphuric  acid,  in 
another ;  the  silicates,  salts  of  silicic  acid,  in  a  third,  etc. 


INTRODUCTION   AND   CHEMICAL   PRINCIPLES.  5 

With  a  knowledge  of  the  valence  of  a  given  metal,  it  is  a  sim- 
ple matter  to  write  the  normal  salt  of  any  known  acid,  as  shown 
by  the  following  table  : 

Hydrochloric,  Sulphuric,  Phosphoric,  Orthosilicic, 

HC1.  HaS04.  H,P04.  H4Si04. 

Sodium,  Na,  univalent,  NaCl  NaaSO4  NasPO,  Na4SiO4 

Calcium,  Ca,  bivalent,  CaCl,  Ca*SO,  Ca3(PO4)a          Ca2SiO4 

Ferric  iron,  Fe,  trivdlent,  FeCls  Fe2(SO4)s  FePO4  Fe4(SiO4)f 

Chemical  Equations. — When  chemical  substances  react  upon 
or  unite  with  one  another,  definite  transformations  take  place, 
which  can  be  expressed  in  the  form  of  equations.  Thus,  when 
calcite  is  dissolved  in  hydrochloric  acid,  or  barite  is  fused  with 
sodium  carbonate,  the  results  are  shown  as  follows : 

CaCO,  +  2HC1  =  CaCla  +  HaO  +  CO,. 
BaS04  +  NaaCO,  =  BaC03  +  ]STaaS04. 

The  practice  of  writing  correct  equations  serves  a  useful  pur- 
pose in  affording  a  knowledge  of  the  manner  in  which  chemical 
reactions  take  place. 

Atomic  Weight. — It  has  been  found  that  an  atom  of  an 
element  possesses  a  definite  relative  weight,  known  as  its  atomic 
weight.  This  is  based  on  an  atom  of  hydrogen,  the  lightest  of  all 
elements,  as  a  standard  (the  weight  of  the  hydrogen  atom  being 
taken  as  1).  The  atomic  weights  of  the  common  elements  have 
been  very  accurately  determined  and  are  generally  given  with 
their  descriptions. 

Molecular  Weight. — The  molecular  weight  of  a  substance  is 
equal  to  the  sum  of  the  atomic  weights  of  the  elements  constituting 
the  molecule.  Thus,  calcium,  carbon,  and  oxygen,  having  the 
atomic  weights  40,  12,  and  16,  respectively,  CaCO3  has  a  molecular 
weight  of  40  + 12  +  48  =  100. 

Relations  between  Chemical    Formulae  and  Percentage  Con .« 
position. — With  a  knowledge  of  the  chemical  formula  of  a  corn 
pound  and   of  the   atomic  weights,  the  percentage   composition 
of  the    different    constituents    can    be  readily  calculated.      For 
example,  sphalerite  is  ZnS.     The  atomic  weights  are  Zn  =  65.4  and 


6  INTRODUCTION    AND  .CHEMICAL   PRINCIPLES. 

S  =  32,  hence  the  molecular  weight  of  ZnS  is  97.4.  In  97.4  parts 
by  weight  of  ZnS  there  are  65.4  parts  of  zinc,  consequently  the 
zinc  in  100  parts  may  be  readily  calculated  by  a  simple  proportion, 
thus  :  97.4  :  65.4  =  100  :  a?,  which  gives  67.1  as  the  per  cent  of  zinc. 
It  is  often  convenient  to  give  the  percentages  of  combinations  of 
the  elements,  especially  the  oxides,  instead  of  the  elements  them- 
selves. This  is  illustrated  by  the  following  examples,  where  the 
percentages  are  derived  from  the  molecular  weights  by  the  propor- 
tion, Total  Mol.  Wt.  :  Mol.  Wt.  of  constituent  =  100  :  x: 

Andradite  Garnet.  Dolomite. 

Ca3FeaSi3Oi2  =  3CaO.Fe2O3.3SiOa.  CaMg(CO3)2  =  CaCO3.MgCO3. 

At.Wt.  Mol.Wt.  At.Wt.    Mol.Wt. 

O;,      8228|X3  =  18»    Si°"       85'4*        O"     M        100    CaCO,,     54.3* 
Fe2,  112  )  1Rn    ,,    n       Q1  -          O3,     48 

{  16°    Fea°"     31'5 


O,,      48  {  a"         '  Mg,  24 

1ftft  p  n  QO  .,  C,  \t\ 

168  Ca0'  S3-1  O,,  48  J 

508  100.0  184  100.0 


Ca,     40)        o      1ftft     p  n        QO  .,  C,       \t          84    MgC03,     45.7 

O,       16  \    x  3  =168     Ca0'       S3-1  O,,     48  J    _  _ 


Quantitative  Chemical  Analyses.  —  The  chemical  composition 
of  minerals  is  determined  by  means  of  quantitative  analyses,  and 
many  of  these  will  be  found  recorded  in  the  larger  treatises 
on  mineralogy.  Now,  since  a  percentage  analysis  gives  the 
weights  of  the  different  constituents  in  one  hundred  parts,  and 
each  constituent  has  its  definite  relative  weight  (atomic  or  molec- 
ular), therefore  the  relative  number  of  atoms  or  molecules  may  be 
found  by  dividing  the  percentages  by  their  atomic  or  molecular- 
weights.  The  quotients  indicate  the  ratio  of  the  constituents, 
which  is  usually  a  simple  one. 

The  following  examples  of  actual  analyses  will  illustrate  this  : 

Sphalerite.  Andradite  Garnet. 

Found.    At.Wt.       Ratio.  Found.     Mol.Wt.  Ratio. 

S,     32.  93  -f-  32     =1.029  SiOt,    35.44-5-    60  =  .591 

Zn,  66.69  -*-  65.4  =  1.019  Fe2O3,  31.85  -*-  160  =  .199 

Fe,       .42  CaO,     32.85  H-    56  =  .587 

MgO,        .20 
100.04  _ 

100.34 


INTRODUCTION   AND   CHEMICAL   PRINCIPLES.  7 

The  ratios  derived  from  these  analyses  are  as  follows : 

S  :  Zn  =  1.029  : 1.019  =  1.00  :  0.99,  or  very  nearly  1 : 1. 
SiO2 :  Fe2O, :  CaO  =  .591 :  .199  :  .587  =  2.95  : 1.00  :  2.97,  or  nearly 
3:1:3. 

The  formula  of  sphalerite  is,  therefore,  ZnS,  and  that  of  the 
garnet,  3CaO.Fe2O3.3SiO2,  or  Ca3Fe2Si3O12.  These  analyses  may 
be  compared  with  the  theoretical  values  calculated  in  the  previous 
paragraphs. 

Isomorphism  (firos,  equal,  +  yuop0^,  form). — Substances  which 
are  analogous  in  chemical  composition  frequently  show  a  simi- 
larity in  crystallization.  This  is  known  as  isomorphism.  Thus, 
the  alums,  KAl(S04)2.12HaO,  and  (NH4)Al(S04)f.12H9O,  are  iso- 
morphous.  They  must  have  similarity  in  molecular  arrangement, 
for  they  not  only  crystallize  in  the  same  shapes,  but,  from  a  solu- 
tion containing  both  salts,  a  crystal  may  be  grown  consisting 
partly  of  potash  and  partly  of  ammonia  alum.  This  tendency  of 
two  salts  to  crystallize  together  constitutes  the  strongest  proof  of 
their  isomorphism. 

Isomorphism  plays  a  very  important  part  in  mineralogy. 
Many  species  are  mixtures  of  two  or  more  isomorphous  chemical 
molecules,  and,  owing  to  this  fact,  the  physical  properties  (espe- 
cially color,  specific  gravity,  and  fusibility)  are  often  found  to 
vary  widely.  For  example,  sphalerite  when  it  has  the  composi- 
tion ZnS  is  colorless  or  nearly  so.  It  usually,  however,  contains 
isomorphous  FeS,  and  the  color  becomes  darker  as  the  percentage 
of  iron  sulphide  increases.  Columbite,  FaN"baO, ,  and  the  isomor- 
phous tantalite,  FeTa2O6,  have  the  specific  gravities  5.3  and  8.2, 
respectively ;  while  intermediate  mixtures  of  the  two  molecules 
have  specific  gravities  ranging  between  these  values. 

Concerning  isomorphous  mixtures,  it  is  often  stated  that  one 
element  replaces  the  other;  i.e.,  sphalerite  is  ZnS,  but  part  of  the 
zinc  may  be  replaced  by  iron.  To  express  the  composition  of 
these  mixed  compounds,  two  methods  are  commonly  employed ; 
either  the  isomorphous  elements  are  designated  by  some  symbol, 


INTRODUCTION   AND    CHEMICAL   PRINCIPLES. 


as  R,  or  they  are  enclosed  in  parentheses.  For  example,  sphaler- 
ite is  said  to  have  the  composition  RS,  where  R  =  Zn  and  Fe,  or 
(Zn,Fe)S,  giving  importance  to  the  prevailing  constituent  by  plac- 
ing it  first,  and  often,  also,  by  using  larger  type.  By  the  latter 
formula,  it  is  not  meant  that  sphalerite  contains  one  atom  of  zinc, 
one  of  iron,  and  one  of  sulphur,  but  that  the  zinc  and  iron  taken 
together  are  equivalent  to  one  atom  of  a  bivalent  metal. 

The  following  examples  will  illustrate  the  methods  of  deriving 
•formulae  from  analyses  of  isomorphous  compounds : 


Brown  Sphalerite. 
Roxbuiy,  Conn. 

Found.  At.Wt.  Ratio. 
S,  33.36  -T-  32  =1.043 
Zn,  63.36-^65.4  =  .969 
Fe,  3.60 -h  56  =  .064 

100.32 


S, 


II. 

Black  Sphalerite. 

Felsobanya. 
Found.     At.Wt.         Ratio. 
33.25-i-    32     =1.039 


III. 

Almandine  Garnet. 
Fort  Wrangel,  Alaska. 

Found.     Mol.VVt.    Ratio. 
SiOa,    39.29 -T-    60  =  .655 


Zn,  50.02  -t-    65.4  = 

Fe,  15.44 -H    56     = 

Cd,  .30  -5- 112     = 

Pb,  1.01  •*•  207     = 

100.02 


756 

A13O3, 

21.70-*- 

102  = 

.213 

276 

FeO, 

30.82  -f- 

72  = 

.428 

003 

MnO, 

1.51  -s- 

71  = 

.021 

005 

MgO, 

5.26-5- 

40  = 

.131 

CaO, 

1.99-r- 

56  = 

.03$ 

100.57 


In  I,  the  ratio  of  S:Zn  +  Fe  =  1.043:1.033  =  1.00:0.99  or 
almost  exactly  1:1.  The  formula  is  therefore  (Zn,Fe)S.  The 
ratio  of  Zn  :  Fe  =  .969  :  .064  or  approximately  15  : 1,  and  the 
composition  of  the  mineral  may  be  regarded  more  exactly  as 
ISZnS  +  FeS. 

In  II,  the  ratio  of  S  :  Zn  +  Fe  +  Cd  +  Pb  =  1.039  : 1.040  or  1  : 1. 
The  formula  is  therefore  (Zn,Fe,Cd,Pb)S,  or,  since  Zn  :  Fe  =  .756  :  .276 
or  nearly  11 : 4,  the  composition  is  more  exactly  HZnS  +  4FeS  -f- 
traces  of  CdS  and  PbS. 

In  III,  FeO,  MnO,  MgO,  and  CaO  are  isomorphous  and  will  be 

regarded  as  RO.     The  ratio  of  SiO, :  A12O9 :  RO  =  .655  :  .213  :  .616 

—  3.07:1.00:2.89.     The  ratio  approximates  to  3:1:3,  and  the 

-  formula  is  3RO.AlaO,.3SiO,,  or  R,Al,Si,0Jt,  where  R  =  Fe,  Mg,  Ca, 

and  Mn. 

Dimorphism  and  Trimorphism.— Minerals  which  have  the 
same  percentage  composition,  but  occur  in  two  essentially  differ- 


INTRODUCTION   AND   CHEMICAL   PRINCIPLES.  9 

ent  crystalline  forms,  are  said  to  be  dimorphous.  Thus,  carbon 
crystallizes  in  the  isometric  system  as  diamond,  which  is  hard  and 
transparent,  with  specific  gravity  —  3.52;  and  in  the  hexagonal 
system  as  graphite,  which  is  soft  and  opaque,  with  Sp.  Gr.  =  2.15. 
Calcium  carbonate,  CaCO3,  crystallized  in  the  hexagonal  system, 
Sp.  Gr.  =  2.71,  is  calcite  ;  and  in  the  orthorhombic  system,  Sp.  Gr. 
=  2.94,  it  is  aragonita  Iron  sulphide,  FeSQ,  crystallized  in  the 
isometric  system,  Sp.  Gr.  =  5.02,  is  pyrite,  and  in  the  orthorhom- 
bic system,  Sp.  Gr.  =  4.90,  it  is  marcasite.  Titanic  oxide,  Ti02, 
crystallizes  in  two  entirely  independent  modifications  in  the 
tetragonal  system,  with  Sp.  Gr.  =  4.20,  as  ru tile,  and  with  Sp.  Gr. 
~3.90,  as  octahedrite,  and  also  in  the  orthorhombic  system, 
Sp.  Gr.  =4.0,  as  brookite.  The  last  case,  where  three  independ- 
ent modifications  of  TiO2  occur,  is  an  example  of  trimorpliism. 
Dimorphism  and  trimorphism  may  be  due  either  to  variations  in 
the  number  of  atoms,  to  variations  in  the  arrangement  of  the 
latter  in  the  chemical  molecule,  or  to  variations  in  the  arrange- 
ment of  the  particles  in  the  structure  of  the  crystal.  No  exact 
means  for  determining  the  size  of  the  chemical  molecule  in  solid 
substances  exists  at  present.  TiO2 ,  for  example,  is  the  simple 
empirical  formula  for  rutile,  but  its  true  composition  is  undoubt- 
edly some  multiple  of  TiOa. 


CHAPTER  II. 

APPARATUS    AND    REAGENTS,    AND    THE    PRINCIPLES    INVOLVED     IN 

THEIR  USE. 

PART  1.    APPARATUS. 

Although  a  great  deal  of  blowpipe  apparatus  has  been  devised, 
only  that  will  be  described  in  the  present  work  which  is  necessary 
or  convenient  for  making  the  simple  tests  for  the  identification  of 
the  elements  and  the  determination  of  minerals.  In  performing 
most  of  the  experiments  a  simple  and  inexpensive  outfit  will 
suffice,  which,  if  necessary,  can  be  packed  in  small  space,  so  as  to 
be  portable.  Moreover,  a  little  ingenuity  will  often  enable  one  to 
supply  the  place  of  much  apparatus. 

The  Mouth- Blowpipe. — This  instrument,  for  centuries  em- 
ployed only  by  artisans  in  soldering  and  in  other  operations  re- 
quiring an  intense  heat,  has  been  for  a  period  of  considerably  over 
one  hundred  years  an  invaluable  means  of  scientific  research.* 
It  is  of  the  greatest  service  to  the  mineralogist  and  chemist  for 
the  identification  of  minerals  and  the  detection  of  their  ingredients, 
and  may  even  be  used  for  the  quantitative  separation  of  several 
metals  from  their  ores.f 


*  For  a  brief  history  of  the  use  of  the  blowpipe,  see  Berzelius's  work,  Die 
Anwendung  des  Lothrohrs;  or  the  translation  by  J.  D.  Whitney,  Boston,  1845. 
A  more  complete  history  is  found  in  Kopp's  Geschichte  der  Chemie,  II,  p.  44, 
Braunschweig,  1844,  and  also  in  von  Kobell's  Geschichte  der  Mineralogie, 
Miinchen,  1864. 

t  Quantitative  blowpipe  analysis  is  beyond  the  scope  of  the  present  work.  Those 
interested  in  Plattner's  methods  of  assaying  ores  of  gold,  silver,  copper,  lead,  cobalt, 
nickel,  iron,  etc.,  by  means  of  the  blowpipe,  are  referred  to  his  work,  Probirkunsi 
wit  dem  Lothrohre;  German  edition,  by  Th.  Richter;  American  translation,  by 
H.  B.  Cornwall. 

10 


APPARATUS. 


11 


With  no  other  fuel  than  that  furnished  by  a  common  lamp  or 
candle,  the  blowpipe  renders  it  possible  to  produce  in  a  moment  a 
most  intense  heat.  In  the  blowpipe  flame,  not  only  are  many 
refractory  bodies  melted  or  volatilized,  but  entirely  opposite 
chemical  effects,  oxidation  and  reduction,  jnay  be  produced. 
Almost  all  chemical  substances  may  be  made  to  manifest  some 
characteristic  phenomena  under  its  influence,  either  alone  or  in  the 
presence  of  certain  other  substances  known  as  reagents,  and  thus 
their  nature  may  be  detected. 

The  blowpipe  is  represented  in  its  usual  form  in  Fig.  1.  The 
parts  a  and  b  fit  into  the  chamber  c  with  ground  joints.  Any 
moisture  from  the  breath  which  condenses  in  a  collects  in  c,  and 
may  be  removed  by  disjointing  the  parts. 
The  instrument  is  also  furnished  with  a  tip 
or  jet  (the  most  important  part),  which  fits 
on  b  by  means  of  a  ground  joint,  and  is 
shown  at  d  in  correct  proportion  and  twice 
the  natural  size.  The  hole  at  the  end  of 
the  tip  should  be  slightly  tapering  and  from 
0.4  to  0.6  mm.  in  diameter.  It  should  be 
bored  in  such  a  manner  that  its  axis  is  in 
line  with  the  axis  of  the  tube  b  when  the 
parts  are  fitted  together.  Very  durable  and 
inexpensive  tips  are  made  of  brass.  Those 
bored  and  turned  out  from  solid  platinum 
are  expensive  and  scarcely  better  than  brass, 
while  light  ones  spun  from  platinum  foil  are 
unsatisfactory.  Tips  are  very  apt  to  become 
stopped  with  dust  or  foreign  matter,  and 
new  ones  often  contain  bits  of  metal  turn- 
ings, or  need  to  be  reamed  out  to  the  proper  size  and  taper. 
Cleaning  and  adjusting  can  best  be  accomplished  by  means  of 
a  four-sided,  slightly  tapering  reamer,  which  may  be  made  by 
filing  down  the  sides  of  a  large  steel  needle  or  pin.  For  the 
successful  working  of  the  blowpipe,  it  is  also  important  that  the 


FIG.  1. 


12  APPARATUS. 

hole  through  b  should  not  be  eccentric,  and  that  there  should  be 
nothing  to  disturb  the  passage  of  air. 

The  instrument  as  shown  in  Fig.  1,  but  without  the  trumpet 
mouthpiece,  is  of  the  original  form  proposed  in  the  last  century 
by  Gahn,  and  employed  by  Berzelius.  Fatigue  is  apt  to  result  in 
using  it,  as  considerable  effort  is  required  to  keep  the  lips  closed 
about  the  tube  for  any  length  of  time. 

Fig.  1  represents  the  blowpipe  provided  with  the  trumpet 
mouthpiece,  e,  recommended  by  Plattner.  This  is  made  of  horn 
or  hard  rubber,  35  mm.  in  its  outer  diameter,  and  should  have 
such  a  curvature  that,  when  placed  against  the  lips,  it  does  not 
give  an  unnecessary  or  unequal  pressure. 

A  very  good  mouthpiece  may  be  made  from  a  piece  of  glass 
tubing  5  cm.  long,  and  of  suteh  diameter  as  fits  the  blowpipe  tube. 
It  should  first  be  strongly  heated  for  half  its  length  in  the  flame 
of  a  lamp,  and  when  quite  soft  flattened  between  two  smooth  me- 
tallic surfaces,  to  give.it  the  form  shown  in  Fig.  2.  The  other 
end  should  then  be  cemented  into  the  blowpipe  by  means 
of  sealing-wax.,  This  kind  of  mouthpiece,  when  inserted 
between  the  lips,  displaces  them  but  slightly  from  their 
customary  position,  and  causes  very  little  fatigue.  .  . 

The  blowpipe  is  usually  made  of  brass,  or  preferably  of 
German  silver:     The  length  of  the  instrument  should  be 
measured  by  the  visual  distance  of  the  operator,  the  ordi- 
FIG.  2.    nary  length  being  from  20  to    22  cm.,  exclusive  of  the 
mouthpiece. 

The  common,  artisan's  blowpipe,  Fig.  3,  consists  of  a  tapering 
and  curved  tube  of  brass,  terminating  in  an  orifice  as  large  as  a 
small  needle.  When  well  constructed,  this  simple  instrument 
answers  most  purposes,  and  is  often  made  without  the  bulb 
near  the  bend,  which  is  intended  to  collect  the  moisture  condens- 
ing from  the  breath. 

A  great  deal  of  ingenuity  has  been  expended  in  devising 
different  forms  of  blowpipes  and  mouthpieces,  each  supposed  to 
have  some  special  feature  either  of  excellence  or  of  cheapness  to 


APPARATUS. 


13 


J 


recommend  it.     However,  if  the  blowpipe  has  a  good  tip,  the  form 
is  of  little  importance,  provided  the  operator  is  skil- 
ful and  has  become  accustomed  to  the  use  of  his  in- 
strument. 

Blowing.— In  blowpipe  operations  it  is  often  neces- 
sary to  maintain  an  uninterrupted  stream  of  air  for 
several  successive  minutes.  To  be  able  to  do  this  easily 
requires  some  practice.  It  is  best  learned  by  fully  dis- 
tending the  cheeks,  closing  the  communication  between 
the  mouth-cavity  and  windpipe  by  means  of  the  palate, 
and  breathing  through  the  nose.  When  one  is  accus- 
tomed to  keeping  the  cheeks  thus  inflated,  the  mouth- 
piece of  the  blowpipe  may  be  pressed  against  or  inserted 
between  the  lips,  and  the  same  thing  repeated  without 
attempting  to  blow  or  do  more  than  keep  the  cheeks 
distended.  To  the  experienced  operator,  continuous 
blowing  is  hardly  an  effort.* 

Fuel  and  Lamps. — The  most  convenient  combustible 
is  ordinary  illuminating-gas  burned  in  a  Bunsen  burner,  FIG.  3. 

Fig.  4.  The  gas  issues  from  a  small  orifice 
near  the  lower  end  of  the  tube,  and  mixes 
with  a  large  proportion  of  air  which  enters 
through  holes  at  7i.  Usually  the  lamp  is 
provided  with  a  ring  at  ^,  fitting  loosely 
over  d,  and  by  turning  this  the  supply  of  air 
can  be  varied.  The  mixture  of  gas  and  air 
should  be  so  regulated  that  the  burner  gives 
a  non-luminous,  blue  flame,  with  a  distinctly 
outlined  inner  cone  about  5  cm.  high. 
FlG  4  For  use  with  the  blowpipe,  an  additional 

*  Various  mechanical  contrivances  have  been  devised  where  the  air  is  supplied 
from  bellows,  but  they  are  regarded  as  unnecessary.  The  strength  of  the  blast  needs 
to  be  often  varied  in  order  to  bring  about  different  effects,  and  with  the  breath  this 
can  be  most  readily  accomplished.  Only  students  showing  enterprise  and  patience 
sufficient  to  master  the  use  of  ordinary  instruments  will  be  likely  to  make  much 
progress  in  blowpipe  analysis. 


APPARATUS. 


FlG.  5. 


tube,  e,  is  supplied,  which  fits  loosely  inside  of  d,  and  goes  down 
below  the  holes  at  7^,  thus  cutting  off  the  supply  of  air,  and 
causing  the  gas  to  burn  with  a  luminous  flame.  The  tube  is  flat- 
tened at  the  top,  and  one  side  is  made  a  little  lower  than  the 
other,  so  that  the  blowpipe  flame  can  be  directed  downward  when 
necessary.  A  slightly  raised  notch  at  the  upper  side  serves  as  a 
rest  for  the  blowpipe  tip. 

A  burner  like  the  one  shown  in  Fig.  5  is  con- 
venient, but  as  it  gives  only  a  luminous  flame  it 
is  not  suitable  for  heating  glass  tubes,  etc.,  and 
an  additional  Bunsen  burner  is  necessary. 

When  gas  is  not  at  hand,  olive-  or  rape-oil, 
burned  in  a  lamp  with  a  rectangular  wick,  5  X  10 
mm.  in  diameter,  may  be  used.  Fig.  6  represents 
the  form  of  lamp  proposed  by  Berzelius  and 
improved  by  Plattner.  The  openings  for  the 
wick  and  for  the  admission  of  oil  are  provided  with  close-fitting 
screw-caps,  and  the  apparatus 
can  be  taken  apart  and  packed  in 
small  space  for  transportation. 

Fig.  7  represents  a  lamp  made 
by  the  Buffalo  Dental  Manu- 
facturing Co.,  which  gives  satis- 
factory results. 

A  form  of  lamp  adapted  for 
portable  blowpipe  apparatus  is 
represented  in  Fig.  8.  Paraffin  is 
used  as  fuel,  and  must  be  melted 
before  lighting,  but,  when  once 
ignited,  the  heat  from  the  flame 
will  keep  a  sufficient  quantity  of 
the  paraffin  in  a  liquid  condition.  FIG.  6. 

When  more  convenient  material  is  not  at  hand,  candles  of  good 
quality  will  answer  for  most  purposes.  A  large  candle  with  a  flat 
wick  can  be  easily  made,  and  is  some  improvement  on  the  ordinary 


APPARATUS. 


15 


form.    For  heating  glass  tubes,  boiling  liquids  in  test-tubes,  etc., 
it  is  desirable  to  have  a  flame  which  does  not  deposit  soot,  and  if 


FIG.  7. 


FIG.  8. 


a  Bunsen  burner  cannot  be  used,  an  alcohol  lamp,  Fig.  9,  with  a 
circular  wick  10  to  15  mm.  in  diameter,  is 
needed.  Such  a  lamp,  however,  is  not  adapted 
for  use  with  the  blowpipe,  as  the  flame  is  not 
rich  enough  in  carbon  to  give  suitable  re- 
duction effects. 

Platinum-pointed  Forceps. — These  are  in- 
dispensable for  holding  fragments  of  minerals 
which  are  to  be  heated  before  the  blowpipe. 
Fig.  10  represents  the  usual  form.  They  are  FlG  9 

made  of  steel,  and  should  be  nickel-plated.  The  platinum  points 
are  opened  by  pressure,  and  are  rendered  self-closing  by  means  of 
a  spring,  which  should  not  be  too  strong.  The  platinum  needs 
occasional  cleaning,  which  is  best  done  by  scouring  with  sea-sand. 


FIG.  10. 

The  steel  ends  are  useful  for  picking  up  and  handling  fragments 
of  minerals  and  for  detaching  pieces  from  specimens.  The  only 
precaution  that  is  needed  in  the  use  of  the  forceps  is  never  to  allow 
minerals  with  metallic  luster  to  fuse  against  the  red-hot  platinum, 
since  the  latter  may  form  a  fusible  alloy  with  lead,  arsenic, 


16  APPARATUS. 

antimony,  or  other  readily  reducible  elements.  If  the  platinum 
does  become  alloyed,  it  is  best  to  cut  off  the  ends  of  the  forceps, 
and  reshape  them  with  a  file. 

Platinum  Wire. — This  is  used  for  supporting  beads  of  fused 
borax,  salt  of  phosphorus,  or  other  fluxes,  and  for  introducing 
powders  into  the  flame.  A  kind  about  0.4  mm.  in  diameter 
(weighing  0.247  grs.  for  every  10  cm.)  is  best. 

Loops. — For  the  support  of  fluxes,  loops,  Fig.  11,  are  used, 
which  are  made  by  bending  the  platinum  wire  over  a 
conical  point.  As  a  rule,  these  loops  should  be  from  3  to 
4  mm.  in  diameter.  The  beads  may  generally  be  removed 
by  straightening  out  the  wire,  or  sometimes  by  dissolving 
them  in  acid. 

The  double  loop  is  made  by  grasping  the  wire  in  the 
FIG.  11.    steel  end  of  the  platinum-pointed  forceps,  and  making  a 
double  turn  about  the  latter.     It  is  only  recommended  to  serve  as 
an  additional  support  when  a  considerable  quantity  of  material  is 
to  be  fused  with  some  flux.  _^ 

Holders. — A    contrivance    like  mmmit 
Fig.  12  is  convenient  for  holding 

platinum  wire.  Short  pieces  of  wire  may  also  be  fused  into  the 
end  of  a  glass  tube  or  rod. 

Platinum  Spoons.— These  may  be  usefully  employed  in  a  few 
operations  where  fusions  are  to  be  made.  Preferably 
the  spoon,  Fig.  13,  should  have  a  bowl  18  to  20  mm. 
in  diameter,  and  need  not  weigh  over  1.25  grams.  It 
FIG.  13.  is  held  in  tne  platinum  forceps,  and  the  fusions  may- 
be soaked  out  by  digestion  in  a  test-tube 
with  water  or  acids.  Spoons  with  long  han- 
dles, Fig.  14,  are  often  recommended,  but  FlG-  14- 
they  are  necessarily  heavier,  and  are  not  very  serviceable  if  the 
bowls  are  small. 

Charcoal. — This  is  used  in  many  operations  as  a  support  for 
the  assay,  and,  moreover,  the  carbon  often  assists  in  bringing 
about  reductions.  For  most  purposes,  any  piece  of  well-burned 


APPARATUS.  17 

charcoal  that  does  not  snap  nor  become  fissured  in  the  flame  will 
suffice.  The  kinds  made  from  basswood,  pine,  or  willow  are 
recommended.  It  is  a  good  plan  to  have  the  material  sawed  out 
into  rectangular  blocks  of  about  10  X  3  X  2  cm.  Excellent 
charcoal,  prepared  especially  for  blowpipe  work,  can  be  procured 
from  dealers. 

Usually  the  assay  is  best  heated  on  a  smooth,  flat  surface, 
although  occasionally  a  slight  depression  or  cavity,  which  may  be 
cut  with  a  penknife,  is  needed. 

A  good  piece  of  charcoal  will  last  for  some  time,  a  clean  sur- 
face being  afforded  by  filing  or  cutting  away  the  part  that  has 
been  used. 

For  the  uses  of  charcoal,  see  p.  39. 

Gypsum  Tablets. — These  are  prepared  by  making  plaster  of 
Paris  into  a  thin  paste  with  water,  pouring  this  upon  a  sheet  of 
glass,  and  spreading  it  out  evenly  until  it  is  about  3  or  4  mm. 
thick.  Before  the  plaster  sets,  its  surface  is  ruled  off  by  means  of 
a  knife  into  rectangular  blocks  about  4x8  cm.  across,  which  are 
removed  after  the  plaster  hardens. 

These  tablets  are  admirably  adapted  for  collecting  sublimates,  especially 
colored  ones,  and,  as  recommended  by  Haanel,*  are  used  as  follows: 

The  finely  powdered  material  to  be  tested  is  placed  near  one  end  of  the 
tablet,  moistened  with  a  few  drops  of  hydriodic  acid,  and  heated  at  the  tip 
of  a  small  oxidizing  flame.  The  iodides,  as  they  volatilize,  condense  on 
the  white  gypsum  as  coatings,  some  of  which  are  very  beautiful.  White 
coatings  may  be  collected  on  tablets  which  have  been  previously  blackened 
by  holding  them  over  a  sooty  flame.  As  a  substitute  for  hydriodic  acid, 
Wheeler  and  Luedekingf  have  found  that  ordinary  tincture  of  iodine 
answers  in  most  cases,  and  an  iodide  of  sulphur,  prepared  by  fusing  4  parts 
by  weight  of  iodine  and  6  of  sulphur,  is  of  still  more  general  application. 
Moses  J  suggests  using  a  flux  prepared  by  mixing  2  parts  of  sulphur,  1  of 
potassium  iodide,  and  1  of  potassium  bisulphate. 

Glass  Tubing. — A  supply  of  hard  glass  tubing,  varying  from 
3  to  6  mm.  in  internal  diameter,  is  needed  for  making  closed  and 
open  tubes. 

*  Trans.  Roy.  Soc.  Canada,  Section  III,  p.  65,  1883. 

t  Trans.  St.  Louis  Acad.  of  Sci.,  vol.  iv,  p.  676,  1886. 

1  School  of  Mines  Quarterly,  New  York,  vol.  x,  p.  320,  1889. 


18  APPARATUS. 

Closed  Tubes. — These  are  tubes  closed  at  one  end,  Fig.  15, 

and    should    be  about  8  cm. 
long,  and  3  to  4  mm.  in  inter- 
FlG-  15>  nal  diameter.     They  may  read- 

ily be  made  by  heating  a  tube  of  twice  the  required  length,  at  the 
middle,  in  a  Bunsen-burner  flame,  and  turning  it  slowly  so  that 
the  glass  will  be  uniformly  heated.  When  the  glass  becomes 
quite  soft,  the  tube  is  removed  from  the  flame  and  pulled  in  two. 
The  slender  terminations  are  then  removed  by  holding  the  end  of 
the  tube  nearly  through  the  flame,  allowing  the  glass,  where  it  has 
been  pulled  out  and  is  quite  thin,  to  fuse  together,  and  then  pull- 
ing away  the  termination. 

These  tubes  are  used  for  heating  substances  out  of  contact 
with,  or  with  but  limited  access  of,  air.  Substances  are  best  intro- 
duced in  the  form  of  fragments,  which  drop  to  the  bottom  of  the 
tube,  leaving  the  walls  perfectly  clean. 

The  principal  effects  that  may  be  observed,  when  substances 
are  heated  in  closed  tubes,  are  the  distillation  or  giving  off  of 
volatile  products  (gases,  liquids,  or  solids),  which  collect  in  the 
upper,  cold  part  of  the  tube  ;  but  any  change  which  the  material 
undergoes  should  be  carefully  noted. 

For  a  list  of  the  closed- tube  reactions,  see  Chapter  IV,  p.  139. 

Bulb  Tubes. — Tubes  with  a  bulb  at  one  end,  Fig.  16,  are 
employed  in  a  number  of 
operations.  They  may  be 
made  by  heating  the  end 
of  a  tube  like  that  shown 
in  Fig.  15  over  a  blast-lamp  until  the  glass  becomes  quite  soft, 
and  then  blowing  a  bulb  of  the  desired  size.  With  a  Bunsen- 
burner  or  alcohol  flame,  sufficient  heat  cannot  be  obtained  to  make 
these  tubes  from  hard  glass,  but  if  one  is  not  able  to  blow  them, 
they  can  be  procured  from  dealers.  A  good  size  for  the  bulb  is 
from  12  to  18  mm.  in  diameter. 

Open  Tubes. — These  are  tubes,  open  at  both  ends,  which  are 
employed  in  heating  or  roasting  substances  in  a  current  of  air, 


APPARATUS. 


19 


and  thus  bringing  about  oxidation.  The  tubes  should  be  from 
5  to  7  mm.  in  internal  diameter  and  15  to  17  cm.  long.  The  sub- 
stance (best  in  the  form  of  fine  powder,  so  as  to  expose  a 

maximum  surface  to  the  air)  is 
placed  about  4  cm.  from  one  end. 
This  may  be  readily  accomplished 
by  putting  the  powder  upon  a  slip 
of  paper,  folded  into  a  Y-shaped  trough, 
slipping  this  to  the  desired  distance  into 
the  tube,  and  inverting.  The  tube,  held 
in  a  slanting  position  (from  20°  to  30°), 
with  the  powder  in  the  lower  end,  is 
then  heated  for  some  time,  first  just 
above  the  substance  to  insure  a  draft  of  air,  and  finally  directly 
under  it.  Straight  tubes  can  be  used  for  almost  all  experiments, 
but  sometimes  the  powder  has  a  tendency  to  fall  out,  and  then 
a  bent  tube,  Fig.  17,  may  be  used.  The  powder  is  placed  near  the 
bend,  and  the  flame  applied  somewhat  above  it  so  as  to  insure  a 
draft  of  air. 

For  a  list  of  the  open-tube  reactions,  see  Chapter  IV,  p.  141. 
Diamond    Mortar. — The  most  convenient  form  is    shown  in 
Fig.  18.     It  is  made  from  the  very  best  tool-steel,  and  is  almost 


FIG.  17. 


FIG.  18. 


FIG.  19. 


indispensable  for  pulverizing  minerals.     A  small  fragment,  not 
over  5  mm.  in  diameter,  is  placed  in  the  cavity;  the  pestle  is  then 


APPARATUS. 


inserted,  and  struck  several  sharp  blows  with  a  hammer.  If  the 
pestle,  which  should  not  fit  too  closely,  is  twisted  so  as  to  give 
a  sort  of  milling  motion,  a  very  fine  powder  can  be  obtained. 
The  mortar  can  be  readily  cleaned  by  grinding  up  bits  of  glass 
and  wiping  the  cavity  and  pestle  with  a  dry  cloth. 

Mortars  made  in  three  parts,  Fig.  19,  which  are  frequently 
recommended  and  kept  in  stock  by  dealers,  are  not  as  serviceable 
as  the  kind  described  in  the  foregoing  paragraph. 

Agate  Mortar  and  Pestle. — These,  Fig.  20,  are  used  for  reduc- 
ing minerals  to  a  very  fine  powder.  The  mortar 
should  be  from  5  to  8  cm.  in  diameter.  The 
mortar  and  pestle  are  used  for  grinding,  never 
for  pounding  hard  bodies. 

If   a   diamond   or   agate   mortar   is   not    at   hand, 

mineral  fragments  may  be  pulverized  by  wrapping  in  several  folds  of  thick 
paper,  and  hammering  on  an  anvil.  A  cheap  porcelain  mortar  will  also 
serve  for  grinding  all  but  very  hard  minerals. 

Hammer. — A  small,  artisan's  hammer  will  answer  most  pur- 
poses. 

Anvil. — A  small  block  of  hardened  steel,  or  any  convenient  flat 
steel  surface  (as  the  base  of  a  diamond  mortar)  is  suitable. 

Pliers.— Cutting-pliers  are  very  serviceable  for  detaching  and 
breaking  up  small  fragments  of  minerals.     Those 
shaped  like  Fig.  21  are  made  especially  for  this 
purpose,  but  ordinary  pliers,  such  as  are  used  for 
cutting  wire,  are  an  excellent  substitute. 

File. — A  small  three-cornered  file  is  used  for 
cutting  glass  tubes.  A  notch  is  cut  in  one  side  of 
the  tube,  which  is  then  half  pulled,  half  broken 
in  two. 

Magnet. — A  common  horseshoe  magnet,  or  a 
magnetized  knife-blade,  serves  to  recognize  mag- 
netic bodies.  A  magnetic  needle  is  sometimes 
useful  for  delicate  determinations. 

Lens. — A  good  magnifying-glass  will  be  found  very  useful. 


FIG.  21. 


APPARATUS. 


21 


An  achromatic  triplet,  of  about  1  inch  focal  length,  is  best,  but  is 
expensive,  and  a  cheaper  form  of  lens  will  answer. 

Watch-glasses. — A  number  of  these,  from  3  to  4  cm.  in  diam- 
eter, will  be  found  convenient  for  holding  mineral  fragments  and 
powders.  Small  butter-plates  or  white 
porcelain  India-ink  slabs  with  three  or 
more  depressions  serve  the  same  purpose. 

Metal    Scoop.— This,    Fig.    22,    is  well  FIG.  22. 

adapted  for  handling  powders,   and  especially  for  transferring 
them  to  tubes. 

Ivory  Spoon  and  Spatula. — An  ivory  spoon,   Fig.  23,  with  a 
bowl  5  X  10  mm.  inner  diameter,  is  useful  for  handling  powders 

and  dry  reagents.  The  handle,  if 
thin  and  flat,  serves  as  a  spatula 
for  handling  and  mixing  reagents. 


FIG.  28. 

A  knife-blade  also  makes  an  excellent  spatula. 

Test-tubes. — For  making  tests  in  the  wet  way,  test-tubes  are 
very  necessary.  They  should  be 
from  15  to  20  mm.  in  diameter 
and  about  16  cm.  long.  A  large 
feather  will  be  found  very  conven- 
ient for  cleaning  such  tubes.  A 
test-tube  stand,  Fig.  24,  and  some 
form  of  holder,  for  use  when 
liquids  are  to  be  boiled,  should  be  FIG-  24. 

obtained.     One  like  Fig.  25  can  be  cut  from  a  piece  of  pine. 


FIG.  25. 


Beakers  and  Flasks.— A  few  of  these,  of  various  sizes,  will 
prove  of  much  service.  The  largest  ones  need  not  have  a  capacity 
of  over  150  cc. 

Funnel  and   Filter-paper.— A   glass  funnel  about    5    cm.    in 


APPARATUS. 


diameter  and  a  supply  of  filter-papers  are  needed.     It  will  be  well 
to  buy  cut  papers,  7  and  9  cm.  in  diameter,  from  dealers. 

Filtering  and  Washing. — To  make  a  filtration,  a  piece  of 
paper  is  folded  twice  upon  itself,  thus  forming  a  quadrant,  and 
this  is  opened  so  as  to  form  a  conical  cup,  having  three  thick- 
nesses of  paper  on  one  side  and  one  on  the  other.  It  is  snugly 
inserted  into  a  dry  funnel,  and  moistened  with  water.  The 
material  to  be  filtered  is  then  poured  upon  the  paper,  care  being 
taken  not  to  have  it  go  above  the  top.  When  the  liquid  has  all 
run  out,  water  is  added  till  even  with  the  top  of  the  paper,  or 
dropped  around  the  edge  so  as  to  moisten  every  part.  By 
repeating  this  several  times,  the  soluble  materials  are  wholly 

washed   away  from    the    insoluble 

portions. 

Porcelain    Dishes.— Those    with 

handles,  called  casseroles,  Fig.  26, 

are    most    convenient    for    boiling 
FIG.  26.  liquids   and    making   evaporations. 

From  7  to  9  cm.  in  diameter  is  a  good  size. 

Porcelain  Crucibles. — These  should  be  about  3  cm.  .in  diameter, 
and  are  useful  in  a  number  of  ways,  especially  for  obtaining  a 
small  quantity  of  a  precipitate  which  has  been  collected  upon  a 


FIG.  27.  FIG.  28. 

filter-paper  and  needs  to  be  subsequently  examined.  For  this 
purpose  the  paper  is  put  into  the  crucible,  and  the  latter,  sup- 
ported on  a  triangle  made  of  iron  wire,  Fig.  27,  is  heated  over  a 


APPARATUS.  23 

lamp  until  the  carbon  of  the  paper  has  completely  burned  away, 
leaving  the  precipitate  together  with  the  trifling  ash  of  the  paper. 
Lamp-stand. — This  may  be  purchased  from  dealers,  or  one 
like  Fig.  27  may  be  easily  made.  By  slightly  bending  the 
coil  of  wire  which  goes  about  the  upright,  the  proper  degree 
of  tension  may  be  obtained,  so  that  the  ring  will  move  readily 
up  and  down,  and  yet  stay  fixed  in  any  position. 

Wash-bottle. — This,  Fig.  28,  can  be  made  from  a  flask,  or 
from  any  bottle  having  a  neck  wide  enough  to  receive  a  doubly 
perforated  stopper. 

Dropping-bottles  and  bulbs. — A  form  like  that  shown  in  Fig. 
29,  about  35  mm.  in  diameter,  is  convenient 
for  water,  when  only  a  small  quantity  is 
needed.  If  less  than  two  thirds  full,  by 
closing  the  larger  opening  and  inverting,  the 
heat  of  the  hand  will  expand  the  air  and 
drive  out  the  water  drop  by  drop.  Fig.  30 
represents  a  form  with  a  bulb  30  mm.  in  FIG.  29. 

diameter,  and  is  convenient  for  holding  reagents  which 
are  to  be  used  a  drop  at  a  time,     In  order  to  fill  it, 
the    bulb  is  warmed  and  the  end  dipped  under  the 
surface  of  the  liquid,  when,  on  cooling,  a  few 
drops  of  the  latter  will  enter.      This  is  then 
boiled  to  expel    the  air,   and  the  tip  again 
FIG.  30.     brought  quickly  under  the  liquid,  when  the 
condensation  of  the  steam  will  cause  the  liquid  almost 
immediately  to  rush  in.     The  bulb  should  not  be  more 
than  two  thirds  full.     A  convenient  form  of  dropping-    FIG.  31. 
bottle  with  hollow  stopper  is  shown  in  Fig.  31. 

Pipette. — A  glass  tube  of  5  mm.  inner  diameter,  heated  over 

a  lamp  and  drawn  out  to  a  capil- 
lary,   Fig.    32,     will    serve  as    a 
FlG-  33-  pipette,  and  will  be  found  useful 

for  taking  up  small  quantities  of  liquids  and  introducing  them 
into  tubes, 


24  REAGENTS. 

PART  2.    REAGENTS. 

Reagents  are  substances  employed  to  produce  changes  in 
bodies,  in  order  to  test  their  composition.  They  are  known  as 
dry,  gaseous,  or  wet,  according  as  they  are  used  in  the  solid, 
gaseous,  or  liquid  form.  Most  of  them  can  be  obtained,  suffi- 
ciently pure,  at  drug  stores  or  from  dealers  in  chemicals.  The 
solids  and  liquids  should  be  carefully  labelled  and  kept  in  suitable, 
well-stoppered  bottles.  For  greater  convenience,  however,  it  is 
well  to  have  on  hand  a  supply  of  some  of  the  more  common 
dry  reagents  in  wooden  or  glass  pill-boxes  about  4  cm.  in  diameter. 

DRY   REAGENTS. 

Sodium  Carbonate,  Na,COs. — Dry  sodium  carbonate  may  be 
purchased,  or  it  may  be  made  by  heating  the  commercial  bicar- 
bonate in  a  porcelain  dish  until  it  becomes  anhydrous.  Sodium 
carbonate  is  used  for  decomposing  many  substances,  and  owes  its 
action  to  the  tendency  of  sodium  to  unite  with  non-metallic  or 
acid-forming  elements.  Thus,  ZnS  +  ISTa^O,  =  Na,S  +  ZnO  +  CO2. 
Fusions  with  sodium  carbonate  are  frequently  made  in  a  loop  on 
platinum  wire,  and  in  order  to  obtain  a  bead,  it  is  recommended 
to  make  the  material  into  a  thick  paste  with  water,  to  take  this 
up  in  the  loop,  Fig.  11,  and  to  fuse  in  an  oxidizing  flame.  The 
bead  should  be  clear  when  hot,  but  white  and  opaque  when  cold. 
If  heated  in  the  reducing  flame,  it  will  be  brown,  owing  to  the 
presence  of  carbon. 

For  a  list  of  some  of  the  reactions  with  sodium  carbonate,  see 
Chapter  IV,  pp.  145  and  151. 

Borax,  or  Sodium  Tetraborate,  JNaaB407.10H2O.—  The  crys- 
tallized commercial  salt  is  usually  sufficiently  pure,  and  is  broken 
into  coarse  powder  for  use.  Borax  is  generally  fused  into  a  bead 
on  platinum  wire,  and  to  make  this,  the  platinum  loop,  Fig.  11,  is 
heated  and  touched  to  the  salt,  and  the  adhering  material  fused 
before  the  blowpipe  until  a  clear  glass  is  obtained.  The  bead 
should  be  lenticular  in  shape,  and  clear  and  colorless.  To 


REAGENTS.  25 

introduce  the  material  to  be  tested  into  the  bead,  touch  the  latter 
when  hot  to  a  small  particle  of  the  substance,  or  to  a  little  of  the 
powder,  and  heat  before  the  blowpipe.  Borax  dissolves  various 
substances,  especially  the  oxides  of  the  metals,  and  with  many  of 
them  gives  characteristic  colors. 

For  a  list  of  the  tests,  see  Chapter  IY,  p,  148. 

Borax-glass. — This  is  needed  for  only  a  few  experiments.  A 
little  at  a  time  may  be  made  by  fusing  borax  in  a  rather  large 
loop  on  platinum  wire,  and  crushing  the  glass  in  a  diamond 
mortar.  It  may  also  be  purchased. 

Phosphorous  Salt,  or  Hydrogen  Sodium  Ammonium  Phos- 
phate, HNaNH4PO4.4H20 ;  sometimes  called  Microcosmic  Salt — 
This  is  generally  fused  into  a  bead  on  platinum  wire.  The  bead  is 
made  in  the  same  way  as  the  borax  one,  but  the  material  becomes 
very  liquid,  and  is  apt  to  drop  from  the  loop  when  first  heated. 
This  may  be  avoided,  however,  by  heating  gently  at  first,  and 
holding  the  bead  just  above  the  flame,  so  that  the  escaping  steam 
and  the  force  of  the  blast  may  buoy  up  the  liquid.  The  salt  is 
changed  by  fusion  to  SODIUM  METAPHOSPHATE,  NaPO3.  The 
reactions  with  sodium  metaphosphate  beads  are  mostly  similar  to 
those  with  borax,  and  a  tabulated  list  of  them  will  be  found 
in  Chapter  IV,  p.  149. 

Test-papers. — Blue  litmus-  and  yellow  turmeric-paper  may  be 
purchased  from  the  dealers.  The  former  is  turned  red  by  acids, 
and  the  latter  reddish-brown  by  alkalies.  The  turmeric-paper  also 
serves  for  the  recognition  of  boracic  acid  and  zirconium.  For  use, 
these  papers  are  conveniently  cut  into  narrow  strips. 

Potassium  Bisulphate,  HKSO4,  and  Potassium  Pyrosulphatef 
K2S20, ;  sometimes  called  Acid  Sulphate  of  Potash. — This  can  be 
made  by  heating  crystallized  potassium  sulphate  with  half  its 
weight  of  concentrated  sulphuric  acid  (10  grams  K2SO4  and  3  cc. 
H2SO4)  in  a  porcelain  dish  until  vigorous  frothing  ceases.  The 
fusion  solidifies  to  an  opaque  mass,  which  should  be  pulverized 
and  preserved  in  a  well-stoppered  bottle.  Heating  changes 
HKSO4  into  pyrosulphate,  K2S2O,,  and  finally  to  normal  sulphate, 


26  REAGENTS. 

K3S04.  A  variety  of  minerals  are  decomposed  by  fusion  with 
potassium  bisulphate,  and  such  fusions  may  be  made  either  in 
the  platinum  spoon,  porcelain  crucible,  or  often  even  in  a  test- 
tube. 

Potassium  Bisulphate  and  Fluorite. — The  finely  pulverized 
materials,  mixed  in  the  proportion  of  3  parts  of  the  former  to  1  of 
the  latter,  are  useful  for  detecting  boron  in  some  of  its  combina- 
tions, and  it  is  well  to  have  a  small  supply  of  the  mixture  on 
hand.  The  mixture  when  heated  liberates  hydrofluoric  acid. 
2HKS04  +  CaF,  =  K,SO4  +  CaSO4  +  2HF. 

Potassium  Iodide  and  Sulphur. — The  pulverized  materials, 
mixed  in  equal  proportions,  are  used  for  detecting  bismuth  and 
lead. 

Oxide  of  Copper,  CuO. — This  is  useful  for  detecting  chlorine. 
A  little  of  the  oxide  may  be  purchased,  or  made  by  dissolving 
copper  in  nitric  acid,  evaporating  the  solution  to  dryness,  and 
igniting  to  redness  in  a  porcelain  dish.  A  little  powdered  cuprite 
or  malachite  will  answer  equally  well. 

Potassium  Nitrate,  KNO3. — This  is  used  occasionally  for 
fusing  with  minerals  when  an  oxidation  is  required. 

Bone-ash, — This  is  needed  for  the  silver  assay.  It  will  be  best 
to  purchase  a  small  supply  from  a  dealer. 

Granulated  Tin,  Zinc,  and  Lead. — These  may  be  purchased 
from  the  dealers.  The  first  two  are  used,  generally  with  acids,  in 
making  reductions,  as  they  dissolve  in  acids  with  evolution  of 
hydrogen,  and  change  many  combinations  from  a  higher  to  a 
lower  valence.  Thus,  2FeCl3  +  Zn  =  2FeCl2  +  ZnCl2,  or  possibly 
Fed,  +  H  =  FeCl,  +  HC1.  Lead  is  used  for  the  silver  assay, 
and  should  be  free  from  silver.  This  is  commonly  called  test- 
lead. 

Magnesium. — This  may  be  useful  for  detecting  phosphoric 
acid.  It  is  best  to  have  the  magnesium  ribbon. 


EEAGENTS.  27 

GASEOUS   EEAGENTS. 

Hydrogen  Sulphide,  H2S. — When  a  little  of  this  reagent  is 
needed  it  may  be  generated  in  the  simple  appa- 
ratus shown  in  Fig.  33.  The  bottle  contains  frag- 
ments of  ferrous  sulphide,  FeS,  and  concentrated 
hydrochloric  acid  diluted  with  an  equal  volume 
of  water  is  poured  in  through  the  thistle-tube,  so 
as  to  give  as  nearly  constant  a  flow  of  gas  as  pos- 
sible. FeS  +  2HC1  =  H2S  +  Fed,.  By  means 
of  a  glass  tube  and  a  rubber  connection,  the  gas 
may  be  led  into  any  liquid  in  order  to  bring  about 
a  precipitation. 

Chlorine,  Cl. — This  reagent  is  seldom  needed, 
but  a  little  of  it  may  be  prepared  by  warming 
powdered    pyrolusite,    MnO2,    with   concentrated 
hydrochloric  acid  (p.  101),    and  carrying  off  the        FIG.  33. 
chlorine  by  means  of  a  bent  glass  tube  running  through  a  per- 
forated cork.     CJilorine-water,  or  water  saturated  with  chlorine 
gas,  is  sometimes  used. 

WET  REAGENTS. 

Wet  reagents,  especially  acids,  should  be  kept  in  bottles  with 
ground-glass  stoppers,  and  should  be  handled  carefully.  Acids 
when  boiled  give  off  disagreeable  and  corrosive  fumes,  and  it  is 
quite  essential  that  these  should  be  carried  off  by  a  good  draft, 
which  may  be  accomplished  by  arranging  a  hood  or  small  chamber 
connecting  with  a  chimney-flue.  If  acids  are  spilled  upon  fabrics, 
the  spots  should  be  immediately  moistened  with  ammonia  to 
neutralize  the  acid,  and  then  thoroughly  washed  with  water. 

Water. — Distilled  water  is  best,  but  clean  rain-water  may  be 
substituted.  It  is  convenient  to  keep  a  supply  of  water  in  a  wash- 
bottle,  Fig.  28. 

Hydrochloric  Acid,  HCL — This  reagent  is  a  solution  of  HCi 
gas  in  water.  The  pure  concentrated  acid  of  the  dealers  contains 


28  REAGENTS. 

about  40^  HC1,  and  for  most  operations  it  is  best  to  use  the  acid 
diluted  with  an  equal  volume  of  water. 

Nitric  Acid,  HNOS. — This  is  useful  for  dissolving  many  min- 
erals, and  in  the  concentrated  form  it  is  a  strong  oxidizing  agent. 
The  acid  is  exceedingly  corrosive  and  needs  to  be  handled  very 
carefully, 

Nitrohydrochloric  Acid,  or  Aqua  Regia. — This  is  prepared  by 
mixing  1  part  of  nitric  acid  and  3  of  hydrochloric.  It  is  a  power- 
ful solvent  and  oxidizing  agent. 

Sulphuric  Acid,  H2SO4,  or  Oil  of  Vitriol— This  needs  to  be 
handled  with  much  care.  When  added  to  water,  a  great  deal  of 
heat  is  generated,  and  when  hot  (boiling-point  338°  C.),  water 
should  never  be  added  to  it.  For  many  tests  it  is  well  to  employ 
a  dilute  acid,  made  by  adding  1  volume  of  acid  to  4  of  water. 

Hydriodic  Acid,  HI. — This  is  needed  for  only  a  few  tests,  and 
does  not  keep  well,  as  it  decomposes,  with  separation  of  free 
iodine.  It  may  be  prepared  by  suspending  iodine  in  water,  pass- 
ing hydrogen  sulphide  gas  into  the  liquid  until  the  solution 
becomes  colorless,  and  then  decanting  from  the  separated  sulphur. 
It  is  convenient  to  keep  a  supply  of  this  in  a  dropping-bottle, 
Pig.  31. 

Hydrochlorplatinic  Acid,  H2PtCl6;  often  called  Platinic  Chlo- 
ride.—This  is  useful  for  detecting  potassium  in  presence  of 
lithium  and  sodium.  Its  preparation  is  explained  under  platinum 
(Chapter  III,  p.  103). 

Ammonium  Hydroxide,  NH4OH;  commonly  called  Ammonia.— 
This  reagent  is  a  solution  of  ammonia-gas,  NH3,  in  water.  It  is 
a  strong  alkali,  and  should  not  be  added  to  acids  unless  the  latter 
are  cold  and  dilute. 

Potassium  Hydroxide,  KOH.— This  is  another  strong  alkali. 
Its  solution  does  not  keep  well  in  glass,  and  it  will  be  found  more 
convenient  to  have  the  stick  potash  broken  up  and  preserved  in  a 
well-stoppered  bottle. 

Barium  Hydroxide,  BaO2H2. — A  solution  of  this  may  be  pre- 
pared by  dissolving  the  crystallized  salt  in  20  parts  of  warm  water, 


REAGENTS.  29 

cooling  and  filtering  off  the  insoluble  material,  which  consists 
mostly  of  barium  carbonate.  Calcium  hydroxide,  lime-water, 
CaO,H3,  may  be  substituted,  and  is  prepared  by  shaking  up  a 
small  quantity  of  quicklime  with  water,  allowing  this  to  stand 
for  some  hours,  and  then  decanting  off  the  clear  liquid. 

Ammonium  Sulphide,  (NH4)2S. — This  may  be  prepared  by 
saturating  a  little  ammonia  with  hydrogen  sulphide,  and  then 
adding  two  thirds  the  volume  of  the  same  ammonia.  On  long 
standing  it  turns  yellow,  and  then  contains  an  excess  of  sulphur. 

Ammonium  Molybdate,  (NH4)2Mo04.— This  is  almost  indis- 
pensable for  the  detection  of  phosphates.  It  may  be  prepared  by 
dissolving  molybdic  oxide,  MoO3 ,  in  ammonia,  and  pouring  the 
solution  into  dilute  nitric  acid,  being  careful  to  have  an  excess  of 
the  latter.  The  solution  is  allowed  to  stand,  and  anything  that 
may  separate  out  is  filtered  off. 

Cobalt  Nitrate,  Co(NO3)2. — The  crystallized  salt  is  dissolved 
in  10  parts  of  water,  and  the  solution  kept  most  conveniently  in  a 
dropping-bulb,  Fig.  30.  It  is  used  for  moistening  infusible 
substances,  especially  those  containing  aluminium  and  zinc,  which 
are  afterwards  intensely  ignited  before  the  blowpipe,  and  assume 
characteristic  colors.  Cobalt  nitrate  when  ignited  is  decomposed, 
yielding  a  deposit  of  cobalt  oxide  upon  the  assay,  (Co(NO3)2  = 
OoO  +  2NO2  +  O),  and  this  oxide  unites  with  it,  giving  colored 
compounds  of  unknown  composition.  The  reagent  may  be  applied 
to  a  fragment  of  mineral  held  in  the  platinum  forceps,  but  the 
reaction  usually  succeeds  better  if  the  finely  powdered  mineral  is 
made  into  a  thin  paste  with  the  cobalt  nitrate  solution,  and  a  little 
of  this,  placed  upon  charcoal,  is  intensely  ignited  before  the 
blowpipe.  This  latter  method  is  especially  recommended  for  hard 
and  compact  minerals. 

Aqueous  solutions  of  the  following  salts  may  be  kept  in  glass- 
stoppered  bottles,  or,  if  they  are  to  be  used  only  occasionally,  it 
is  recommended  to  keep  a  supply  of  the  pulverized  dry  salts  on 
hand,  and  to  dissolve  a  small  quantity  in  a  test-tube  when  needed. 

Ammonium  Carbonate,    (NH4)2CO3.— The  commercial,  dry  salt 


30 


REAGENTS. 


is  a  mixture  of  ammonium  bicarbonate,  HNH4C03 ,  and  ammonium 
carbamate,  NH2NH  CO3.  Its  solution  in  water,  however,  may  be 
regarded  as  containing  normal  ammonium  carbonate,  (NH4)2CO3. 

Ammonium  Oxalate,  (NH4)2Ca04.2H2O. 

Di-Sodium  Hydrogen  Phosphate,  NaaHP04.12HaO ;  commonly 
called  Sodium  Phosphate. 

Barium  Chloride,  BaCl2.2H8O. 

Silver  Nitrate,  AgNO3. 

Potassium  Ferrocyanide,  K4Fe(CN)6.3H2O. 

Potassium  Ferricyanide,  K6Fea(CN)ja.—  An  aqueous  solution 
of  this  salt  does  not  keep  well. 

Ammonium  Sulphocyanate,  NH4CNS. 

The  list  of  reagents,  both  wet  and  dry,  might  be  considerably 
enlarged,  but  the  principal  ones  have  been  given,  and  those  not  in 
the  list  which  are  mentioned  in  subsequent  chapters  can  be  easily 
procured.  Any  reagents  used  in  a  well-equipped  chemical  labo- 
ratory may  at  times  be  found  convenient. 

Solution. — Of  the  foregoing  reagents,  water  and  the  acids  are 
commonly  employed  for  dissolving  substances.  The  appropriate 
solvent  for  a  mineral  can  be  learned  only  by  experience  or  by  a 
knowledge  of  the  chemical  composition  of  the  material.  As  most 
minerals  are  insoluble  in  water,  its  use  as  a  solvent  is  limited. 
Hydrochloric  acid  is  most  generally  employed,  and  is  preferred  to 
other  strong  acids,  as  it  is  safer  to  handle.  Nitric  acid  is  needed 
when  an  oxidation  is  required,  as  when  sulphides  or  arsenides  are 
to  be  dissolved.  It  is  seldom  necessary  to  use  sulphuric  acid. 

In  order  to  dissolve  a  mineral  it  is  best  to  treat  some  of  the 
very  finely  powdered  material  in  a  test-tube  with  from  5  to  10  cc. 
of  the  solvent  (it  may  be  necessary  to  try  several  solvents  before 
the  appropriate  one  is  found),  and,  if  the  material  does  not 
dissolve  in  the  cold  liquid,  the  contents  of  the  tube  should  be 
hea/fced  to  boiling,  which,  in  the  majority  of  cases,  greatly  facili- 
tates solution. 

Precipitation. — When  insoluble  compounds  are  formed  by 
adding  reagents  to  solutions,  the  process  is  called  precipitation. 


NATURE   OF   FLAMES.  31 

When  solutions  are  mixed,  precipitation  will  take  place,  provided 
an  insoluble  compound  can  be  formed  by  the  interchange  of  the 
chemical  constituents.  For  example,  when  aqueous  solutions  of 
sodium  chloride  and  silver  nitrate  are  mixed,  a  white  precipitate 
of  silver  chloride  will  be  formed,  because  silver  chloride  is  insol- 
uble in  water.  JNTaCl  +  AgNO,  =  AgCl  +  NaNOs  .  Precipitation 
furnishes  a  means  for  detecting  many  elements,  and  it  is  also 
useful  for  separating  substances,  since  the  insoluble  precipitates 
maybe  collected  on  filter-papers  and  thus  removed  from  solutions. 

PART  3.     ON  THE  NATURE  AND  USES  OF  FLAMES. 

Combustion. — This  is  ordinarily  an  oxidation  process,  and 
where  a  flame  is  produced,  the  latter  results  from  the  combination 
of  carbon  and  hydrogen  of  different  gases  and  vapors  with  the 
oxygen  of  the  air,  the  final  products  of  the  oxidation  being  carbon 
dioxide,  CO2 ,  and  water,  H2O. 

When  a  lamp  -or  candle  is  burning,  the  oil  or  the  melted 
material  of  the  candle  is  carried  up  into  the  wick  by  capillary 
attraction,  and  is  there  converted  by  the  heat  of  the  flame  into 
gas  or  vapor,  which  burns.  Such  gases,  as  w^ell  as  ordinary 
illuminating-gas,  are  not  definite  chemical  compounds,  but 
mixtures,  usually  of  different  combinations  of  carbon  and  hydro- 
gen, and  are  known  as  hydrocarbons.  Water-gas,  with  which 
many  cities  are  now  supplied,  is  made  by  blowing  steam  through 
glowing  coals,  when  the  following  reaction  takes  place  :  H2O  +C  = 
2H  +  CO.  The  resulting  gas  (a  mixture  of  hydrogen  and  carbon 
monoxide),  which  burns  with  a  non-luminous  flame,  has  to  be 
mixed  with  some  volatile  material  rich  in  carbon,  in  order  to 
make  it  luminous, 

The  Candle  Flame.— This,  Fig.  34,  has  been  chosen  as  repre- 
senting a  typical  luminous  flame,  and  may  be  regarded  as 
containing  three  distinct  parts,  as  follows  : 

(1)  An  outer  part,  a,  where  the  gases  are  fully  exposed 
to  the  oxygen  of  the  air,  and  where  the  combustion  is  com- 


32 


NATURE    OF    FLAMES. 


A 

:G-\ 


plete ;  that  is,  where  carbon  is  burned  to  CO2 ,  and  hydrogen  to 
H2O.  These  gases  form  an  invisible  envelope  about  all 
ordinary  flames. 

(2)  An    inner    zone,  £,   the    luminous  part  of  the 
flame,  is  characterized  by  an  incomplete  combustion, 
since  only  a  limited  supply  of   oxygen,    which  pene- 
trates the  outer  envelope,  is  available.     Hence,  carbon 
burns  to  its  lower  oxide,  carbon  monoxide,  CO,  while 
hydrogen  forms  H20.     Moreover,  the  heat  of  the  flame 
decomposes  some  of  the  gas,  with  separation  of  finely 
divided  carbon.     This   being  heated  to  incandescence 
FIG.  34.     renders  the  flame  luminous,  and  will  deposit  as  soot 

upon  any  cold  substance  held  in  the  flame. 

(3)  Still  further  within  the  flame  is  the  zone  c,  which  contains 

the  unburned  gases  as  they  are  first  formed 

by  the  heat  and  rise  up  from  the  wick. 

The    three  zones,  a,  5,  and  c,   naturally 

grade  into  one  another,  and  are  not  separated 

by  sharply  defined  boundaries. 

The  Bunsen-burner  Flame.— This,  Fig.  35, 

has  three  zones  corresponding  to  a,  b,  and 

c,  of  the  candle  flame,  except  that  sufficient 

air    is    allowed    to    mix    with    the    gas    to 

prevent  the  separation  of  carbon  in  b.    The 

flame,  therefore,  is  non-luminous  and  depos- 
its no  soot.  The  outer  envelope,  a,  contain- 
ing C02  and  H2O,  is  invisible;  the  zone  £, 

containing  CO,  some  CO2,  and  H2O,  is  pale 

violet ;   and  the  inner  zone,  c,  containing  a 

mixture  of  unburned  gas  and  air,  is  sharply 

outlined  against  b  by  a  pale  blue  border. 
Special  precautions  should  be  taken  that 

the  flame  does  not  snap  down  and  burn  at 

the  base. 


FIG.  35. 


USES   OF   FLAMES.  33 

The  Blowpipe  Flame. — This  is  produced  by  placing  the  tip 
of  the  blowpipe  into  the  gas  or  lamp  flame,  and  blowing  a  mod- 
erately strong  blast  of  air.  If  a  gas  flame  is  used,  it  should  burn 
from  the  jet  e,  Fig.  4,  p.  13, 
and  should  be  from  3  to  4  cm. 
high.  p 

The  operator  should  be  com-    0 
fortably  seated  at  the  table, 
his  arm  resting  upon  its  edge, 
and  the  blowpipe  grasped  near  FlG*  36> 

the  water-chamber,  between  the  thumb  and  first  and  second 
fingers  of  the  right  hand.  The  blast  should  be  so  regulated 
that  the  flame  will  be  deflected  into  a  slightly .  tapering,  dis- 
tinctly outlined,  blue  cone,  Fig.  36,  in  which  the  zones  a,  &, 
and  c,  correspond  exactly  to  those  of  the  Bunsen-burner  flame. 
The  flame  should  not  appear  luminous,  except,  perhaps,  a  small 
portion  just  above  the  blowpipe  tip,  which  is  not  carried  along 
by  the  draft.  If  the  hole  in  the  tip  is  well  bored,  the  flame  will 
neither  flutter  nor  show  irregularities,  even  when  the  blast  is 
strongest. 

Heating  and  Fusion. — The  hottest  part  of  the  blowpipe  flame 
is  at  r,  Fig.  36,  just  beyond  the  tip  of  the  inner  blue  cone.  At  this 
point,  minerals  are  heated  to  determine  their  fusibility  or  other 
phenomena  which  they  may  exhibit.  Even  platinum  can  be  readily 
melted  if  in  the  form  of  fine  wire  (not  over  0.2  mm.  in  diameter), 
so  as  not  to  radiate  nor  conduct  away  the  heat  too  rapidly. 

In  testing  minerals,  the  size  and  shape  of  the  fragment  to  be 
used  is  a  matter  of  considerable  importance.  If  too  large,  it  is 
difficult,  often  impossible,  to  heat  it  up  to  the  desired  tempera- 
ture, while,  if  too  small,  the  reaction  may  not  show  with  sufficient 
distinctness.  Beginners  almost  invariably  err  in  taking  too  large 
pieces.  Usually  the  reaction  succeeds  best  either  with  a  splinter 
or  a  fragment  with  a  thin  edge,  and  a  size  about  as  large  as  a  lead- 
pencil  point  (1  mm.  in  diameter  and  4  mm.  long)  can  be  recom- 
mended. The  fragment  should  be  held  in  the  forceps  in  such  a 


34  USES   OF    FLAMES. 

manner  that  the  greater  part  of  it  projects  free  beyord  the  plati 

num  tips  in  order  that  heat  may 
not  be  wasted  in  warming  up 
the  metal,  and  so  that  a  point  or 
thin  edge  of  the  mineral  is  turned  in  the 
direction  of  the  flame,  Fig.  37.  Any  change 
which  the  mineral  undergoes  may  be  a  help 
in  its  identification,  and  should  be  care- 
PIG.  37.  fully  noted ;  e.g.,  whether  fusible  or  infu- 
sible, and  in  the  former  case  the  degree  of  fusibility  and  the 
manner  in  which  the  mineral  fuses,  whether  quietly  or  with 
intumescence  (swelling);  whether  to  a  clear,  white,  or  vesicular 
(full  of  bubbles)  glass;  whether  to  a  light-  or  dark-colored  mass 
or  slag,  or  to  a  magnetic  or  non-magnetic  mass. 

Decrepitation. — It  frequently  happens  that  a  mineral,  when 
introduced  into  the  blowpipe  flame,  snaps  or  explodes,  so  that  it 
is  difficult  and  often  impossible  to  secure  a  piece  which  can  be 
held  in  the  forceps  and  heated.  This  phenomenon,  known  as 
decrepitation,  may  be  due  to  unequal  expansion  of  the  material. 
More  often,  however,  it  results  from  the  presence  in  the  mineral 
of  minute  cavities  containing  gases  or  liquids  (commonly  water, 
sometimes  liquid  carbon  dioxide),  the  expansion  of  which  causes 
the  explosion. 

At  times  a  fragment  of  a  decrepitating  mineral  may  be  heated  in  the 
forceps,  if  at  first  very  carefully  introduced  into  the  ordinary  gas  or  lamp 
flame,  so  that  it  becomes  slowly  and  uniformly  heated  before  being  subjected 
to  the  more  intense  heat  of  the  blowpipe  flame.  Another  way  is  to  heat  sev- 
eral large  pieces  in  a  closed  tube  until  decrepitation  ceases,  when,  on  dump- 
ing out  the  fragments,  one  may  be  selected  of  the  right  size  and  shape  to  be 
taken  in  the  forceps  and  heated  before  the  blowpipe.  When  the  above 
methods  fail,  the  following,  suggested  by  Berzelius,  may  be  resorted  to: 
Grind  the  mineral  to  a  very  fine  powder,  make  into  a  thin  paste  with  water, 
then  spread  out  a  drop  of  this  upon  a  clean  charcoal  surface,  and  heat 
before  the  blowpipe,  at  first  very  gently,  finally  as  intensely  as  possible.  If 
fusion  has  not  already  been  observed,  a  coherent  cake  will  usually  be 
obtained,  which  with  care  can  be  lifted  in  the  forceps,  and  its  edge  intro- 
duced into  the  blowpipe  flame. 


USES   OF   FLAMES.  35 

Flame  Coloration. — The  heat  of  the  blowpipe  flame  is  so 
intense  that  many  substances  are  volatilized,  and  several  of  the  ele- 
ments in  them  may  then  be  recognized  by  the  colors  they  impart  to 
the  flame  (compare  table,  Chapter  IV,  p.  136).  The  test  may  be 
made  with  a  fragment  held  in  the  clean  platinum  forceps,  as  shown 
in  Fig.  37,  but  usually  it  succeeds  better  when  a  minute  quantity 
of  the  finely  powdered  material  is  taken  upon  a  clean  platinum 
wire  and  introduced  into  the  Bunsen-burner  or  blowpipe  flame. 
For  the  latter  purpose,  a  wire  may  be  cleaned  by  heating  until  it 
imparts  no  coloration  to  the  flame,  or,  if  there  is  much  material 
adhering  to  it,  it  may  be  boiled  in  any  strong  acid,  then  washed 
with  water  and  heated  (compare  Sodium,  p.115,  §1,6).  The  straight 
wire  is  next  moistened  with  pure  water,  and  its  end  touched  to  the 
powdered  mineral  so  as  to  take  up  a  minute  quantity  of  the 
material,  which  is  then  introduced  into  the  flame.  Often  the 
merest  trace  that  will  adhere  to  a  dry  wire  is  sufficient  to  give  a 
magnificent  flame  color.  The  tests  are,  as  a  rule,  exceedingly 
delicate,  and  the  essential  condition  to  be  fulfilled  is  that  the 
material  shall  be  heated  liot  enough  to  volatilize  the  element  or 
compound  which  gives  the  color.  Often  a  sufficient  temperature 
cannot  be  obtained  when  a  rather  large  fragment  held  in  the 
forceps,  or  considerable  material  supported  in  a  loop  on  plati- 
num wire,  is  heated  before  the  blowpipe. 

The  colors  are  best  seen  in  a  dark  room,  but  as  this  is  usually 
not  convenient  a  dark  screen  (book-cover)  as  a  background  will  be 
found  advantageous. 

Oxidation. — By  oxidation  is  meant  the  union  of  a  substance 
with  oxygen  (compare  Combustion,  p.  31).  Many  substances 
when  heated  before  the  blowpipe  readily  take  on  oxygen  from  the 
air  and  are  oxidized.  The  flame  then  imparts  nothing  to  them, 
but  simply  brings  about  conditions  favorable  for  the  taking  up  of 
oxygen.  For  example,  pieces  of  wood  or  a  copper  wire  under 
ordinary  conditions  may  be  kept  almost  indefinitely,  but  if  they 
are  intensely  heated,  with  access  of  air,  the  former  burns,  or 


36  USES   OF    FLAMES. 

oxidizes,  and  the  latter  is  gradually  converted  into  copper  oxide, 
CuO. 

Oxidizing  Flame. — The  flame  represented  in  Fig.  36  is  usually 
called  the  oxidizing  flame,  and  the  part  favorable  for  oxidation 
is  at  o,  beyond  the  blue  and  violet  cones,  c  and  5,  and  especially 
where  the  air  can  and  the  carbon  monoxide  in  b  cannot  have 
access  to  the  substance. 

Reduction. — Usually  by  the  term  reduction  is  meant  the 
taking  away  of  oxygen.  In  a  more  general  sense,  it  may  refer  to 
the  formation  of  a  metal  from  any  of  its  compounds,  or  to  the 
change  of  some  element  in  chemical  combination  from  a  higher  to 
a  lower  valence.  Thus,  the  conversion  of  CuO  or  Cu2S  to  metallic 
copper,  or  of  FeCl3  to  FeCl2  (ferric  to  ferrous  chloride),  would  be 
spoken  of  as  reductions. 

Reducing  Flame. — By  means  of  the  blowpipe  flame,  reductions 
are  made  by  taking  away  oxygen,  and  this  is  accomplished  by 
heating  substances  so  that  they  are  exposed  to  the  action  of  car- 
bon monoxide.  Carbon  monoxide,  CO,  is  a  reducing  gas,  since  it 
has  a  tendency  to  take  on  oxygen  and  become  carbon  dioxide, 


FIG.  38. 

CO3.  Many  oxides,  therefore,  when  heated  with  CO  give  up  their 
oxygen,  and  are  reduced  either  to  a  metal  or  to  a  lower  oxide.  The 
following  equations  will  illustrate  this:  CuO  +  CO  =  Cu-fCO2,  and 
Fe308  +  CO  =  2FeO  +  CO2.  The  part  of  the  flame  most  favorable 
for  reduction  is  at  r,  Fig.  36,  where  the  heat  is  intense  and  carbon 
monoxide  predominates.  When  a  substance  is  large,  it  is  fre- 
quently impossible  to  make  a  satisfactory  reduction  in  a  flame 
like  that  shown  in  Fig.  36,  for,  while  a  portion  is  exposed  to  the 
action  of  carbon  monoxide  in  the  zone  5,  another  portion  must 


USES   OF  FLAMES.  37 

project  into  the  air  and  will  there  have  a  tendency  to  oxidize. 
In  such  cases,  a  broader  flame,  Fig.  38,  should  be  used.  This  is 
made  by  deflecting  the  gas  or  lamp  flame  by  a  gentle  blast,  and 
regulating  the  latter  so  that  the  flame  is  slightly  luminous,  but 
still  does  not  deposit  soot  upon  the  assay  held  at  r. 

Reductions  are  frequently  made  on  charcoal,  and  the  reducing 
action  of  the  carbon  monoxide  is  then  augmented  by  that  of  the 
glowing  carbon. 

The  following  experiments  will  serve  to  illustrate  the  use  and 
application  of  the  blowpipe : 

a.  To  prove  that  water,  H20,  arid  carbon  dioxide,  C02,  are  products  of 
combustion,  take  a  dry  bottle  and  for  a  few  seconds  deflect  a  small  blow- 
pipe flame  down  into  it,  Fig.   39.     The  water 

which  condenses  on  the  sides  of  the  glass  has 
resulted  from  the  oxidation  of  the  hydrogen  in 
the  gas.  That  the  bottle  also  contains  C02  may  be 
proved  by  adding  a  little  clear  barium  hydroxide 
water,  inserting  the  stopper,  and  shaking,  when 
a  white  precipitate  forms,  which  is  barium  car- 
bonate, BaC03.  C03+Ba02H2  =  BaC03-hH20. 

b.  To  show  the  intense  heat  of  the  blowpipe 

flame,  and  to  acquire  skill  in  the  manipulation  of  FlG- 

the  instrument  and  in  maintaining  a  continuous  blast,  fuse  platinum  wire 
and  fragments  of  minerals  used  in  the  scale  of  fusibility  (p.  230).  The 
platinum  wire  should  not  be  over  0.2  mm.  in  diameter,  and  it  is  best  to  bend 
it  near  the  end  and  hold  it  end  on  toward  the  flame  (compare  Fig.  37). 

c.  To   show   that   the   inner   portion   of    a  flame   contains   a   zone   of 
unburned  gas,  make  use  of  a  Bunsen-burner  flame,  Fig,  35,  and  hold  a  glass 
tube  across  it  at  r  until  it  becomes  quite  soft;  then  remove  from  the  flame, 
and  draw  out  to  a  narrow  tube.     Next,  hold  the  narrow  tube  across  the 
flame  at  s,  and  observe  that  it  softens  in  two  places  where  it  passes  through 
the  edges  of  the  flame,  but  the  portion  within  the  cone  c  neither  fuses  nor 
becomes  red-hot.     By  holding  one  end  of  a  rather  narrow  glass  tube  in  c,  a 
little  of  the  unburned  gas  may  be  drawn  off  to  one  side,  and  burned  at  the 
other  end  of  the  tube. 

(L  To  make  a  flame  test,  take  a  fragment  of  barite,  BaS04,  in  the 
forceps,  and  heat  before  the  blowpipe,  as  shown  in  Fig.  37,  until  a  distinct 
color  is  obtained.  Barium  imparts  a  yellowish-green  coloration  to  the 
outer  part  of  the  flame.  Barite  also  fuses  at  about  3  in  the  scale  of  fusibil- 
ity, and  Is  very  apt  to  decrepitate.  Also  test  the  flame  coloration  by  taking 


38  USES   OF   FLAMES. 

up  powdered  barite  on  platinum  wire,  as  directed  on  p.  35,  and  heating  both 
in  the  blowpipe  and  the  Bunsen-bnrner  flames.  In  the  latter  case,  introduce 
the  material  into  the  edge  of  the  flame,  at  about  r,  Fig.  35. 

e.  To  test  the  reducing  character  of  the  blowpipe  flame,  make  some 
experiments  with  hematite,  Fea03  (a  splintery  variety  is  best),  which  should 
not  be  magnetic  before  heating,  but  becomes  so  upon  reduction  to  a  lower 
oxide,  FeO.  Taking  a  fresh  fragment  for  each  experiment,  hold  it  in  the 
forceps,  and  heat  before  the  blowpipe  for  several  seconds  at  the  points  o,  r, 
and  s,  Fig.  36,  and,  after  cooling,  test  with  a  magnet.  If  the  fragments 
become  at  all  magnetic,  it  shows  that  the  reducing  gas,  carbon  monoxide, 
was  present  in  that  part  of  the  flame  where  they  were  heated.  Fe203  -f-  CO 
=  2FeO  -f-  C02.  The  reduction  is  strongest  at  r,  the  tip  of  the  blue  cone, 
where  the  heat  is  most  intense,  and  diminishes  toward  o,  but  it  is  impossible 
to  make  a  general  statement  of  just  where  reduction  ceases,  as  this  depends 
both  upon  the  size  of  the  flame  and  strength  of  the  blast. 

y.  To  illustrate  reduction  and  oxidation,  select  a  small  splinter  of  hema- 
tite, make  sure  that  it  is  not  magnetic,  and  then  heat  for  an  instant  only 
in  the  reducing  flame,  so  as  to  form  FeO  sufficient  to  make  the  fragment 
only  slightly  magnetic.  It  should  then  be  heated  for  a  considerable  time 
at  a  point  o,  Fig.  36  (beyond  the  point  where  carbon  monoxide  exists),  until 
the  FeO  has  taken  up  oxygen  from  the  air,  and  become  oxidized  to  Fe203, 
when  the  fragment  will  cease  to  be  magnetic.  Considerable  care  and  skill 
are  necessary  for  performing  this  experiment  successfully.  If  the  fragment 
becomes  very  magnetic,  it  will  be  best  to  start  with  a  fresh  one,  for  the 
oxidation  goes  on  slowly,  and  it  will  require  a  long  time  for  its  completion. 
Further,  if  FeO  has  been  fused  on  the  splinter,  it  will  be  almost  impossible 
to  complete  the  oxidation  with  the  blowpipe,  since,  although  the  outer 
surface  may  be  converted  into  Fe203,  the  air  will  not  be  able  to  reach  the 
interior  and  make  the  oxidation  complete. 

g.  To  further  illustrate  oxidation  and  reduction,  make  a  borax  bead  on 
platinum  wire,  as  directed  on  p.  24;  touch  the  bead  when  hot  to  a  very  small 
particle  of  pyrolusite,  Mn02,  and  dissolve  the  latter  in  the  borax  by  heating 
at  about  the  point  0,  Fig.  36.  If  the  experiment  is  successful,  the  bead 
should  have  a  fine  reddish-violet  color,  while  if  it  is  black  or  very  dark, 
too  much  pyrolusite  was  added,  and  a  new  bead  should  be  made.  The  color 
is  due  to  an  oxide  of  manganese  higher  than  MnO,  and  if  the  bead  is  heated 
in  the  reducing  flame,  MnO  will  be  formed,  and  the  bead  will  become  color- 
less. In  order  to  make  a  reduction  of  this  kind,  the  following  suggestion 
is  oifered:  Heat  the  bead  very  hot  at  r,  Fig.  36,  where  reduction  goes  on, 
and  then,  without  interruption,  change  the  position  of  the  blowpipe  and 
the  character  of  the  blast  in  order  to  make  a  more  bulky  flame,  Fig.  38,  so 
that  the  bead  may  be  completely  protected  from  the  oxidizing  action  of  the 
air.  If  the  colorless  bead  is  further  heated,  so  that  the  air  has  access  to  it. 


USES   OF   FLAMES.  39 

the  reddish-violet  color,  characteristic  for  manganese,  will  again  appear 
(compare  p.  93,  §  2).  In  making  both  oxidations  and  reductions,  it  is  a 
great  advantage  to  be  able  to  heat  the  substances  very  hot. 

The  Uses  of  Charcoal. — Both  reductions  and  oxidations  are 
made  on  charcoal.  For  the  former,  the  best  results  are  obtained 
by  inclining  the  charcoal,  and  directing  the  flame  downward,  so 
as  to  strike  the  assay  a  little  beyond  the  tip  of  the  blue  cone,  as 
shown  in  Fig.  40.  The  combined  effect  of  the  flame  and  the  burn- 


FIG.  40. 

ing  charcoal  gives  an  intense  heat,  and  the  reducing  action  may 
be  made  very  strong.  Further,  many  elements  are  volatilized, 
and,  passing  into  the  air,  take  on  oxygen  and  deposit  character- 
istic coatings  of  oxide  on  the  coal. 

For  a  list  of  the  coatings  and  the  effects  of  heating  on  char- 
coal, see  Chapter  IV,  p.  143. 

Roasting. — This  is  a  term  which  is  often  applied  to  the  heat- 
ing of  substances  in  contact  with  air.  It  generally  results  in 
oxidation,  and  is  most  conveniently  done  on  charcoal.  In  order 
to  roast  a  substance,  the  finely  powdered  material  is  spread  out 
on  the  surface  of  the  charcoal  so  as  to  allow  free  access  of  air,  and 
is  then  heated  with  a  small  oxidizing  flame,  Fig.  41,  at  a  consider- 
able distance  beyond  the  tip  of  the  blue  cone. 

The  heat  required  for  roasting  is  very  moderate — scarcely  a  red 
Leat.  If  possible,  the  material  should  not  be  allowed  to  fuse,  as 
it  then  does  not  expose  sufficient  surface  to  the  air.  When  very 
fusible  minerals  are  to  be  roasted,  it  is  often  best  to  mix  them 
with  about  an  equal  volume  of  powdered  charcoal,  which  prevents 


40  USES    OF    FLAMES. 

the  material  from  running  together,  and  subsequently  burns 
away.  Another  way  is  to  fuse  and  continue  to  heat  the  material 
until  the  more  volatile  constituents  are  driven  out,  and  then  to 


FIG.  41. 

pulverize  with  a  little  charcoal,  and  roast  carefully  by  means  of  a 
small  oxidizing  flame. 

Eoasting  is  a  very  important  metallurgical  process,  especially 
in  treating  ores  containing  sulphur,  arsenic,  or  antimony,  as  these 
elements  are  removed  as  volatile  oxides,  leaving  oxides  of  the 
metals  which  are  subsequently  reduced. 

The  following  experiments  will  serve  to  illustrate  some  of  the 
effects  which  may  be  produced  by  heating  on  charcoal: 

a.  To  illustrate  the  formation  of  a  metal,  take  a  very  little  powdered 
malachite  (Cu.OH)2CO,,  and  three  times  as  much  of  a  mixture  of  equal 
parts  of  sodium  carbonate  and  borax  as  a  flux,  moisten  to  a  paste  with  water, 
then  heat  intensely,  as  shown  in  Fig.  40,  until  the  copper  fuses  and  collects 
to  a  globule. 

b.  To  illustrate  the  formation  of  a  metal  and  a  coating  of  oxide,  take  a 
little  powdered  cerussite,  PbC03,  an  equal  volume  of  powdered  charcoal  and 
3  volumes  of  sodium  carbonate,  moisten  to  a  paste  with  water,  then  heat  for 
some  time,  as  shown  in  Fig.  40,  until  the  lead  unites  to  a  globule  and  a 
considerable  coating  of  yellow  lead  oxide  collects  on  the  charcoal. 

c.  To  illustrate  oxidation  or  roasting,  place  some  finely  powdered  pyrites 
FeSa ,  on  a  flat  charcoal  surface,  spread  the  material  out  into  a  thin  layer, 
and  heat  very  gently  with  a  small  oxidizing  flame,  as  shown  in  Fig.  41. 
The  pyrite  is  thus  oxidized,  yielding  sulphurous  anhydride  gas,  SO, ,  detected 
by  its  odor,  and  a  residue  of  Fe,08,  or  a  mixture  of  Fe20s  with  FeO.     If 
the  roasting   is   continued  until  the  material  no  longer  emits  an  odor  of 
burning  sulphur,  the  oxidation  will  be  complete,  or  nearly  so,  and  the  resi- 
due will  have  the  dark  red  color  of  ferric  oxide. 


CHAPTEK  III. 


REACTIONS  OF  THE  ELEMENTS. 

For  convenience  of  reference,  the  subject  matter  of  this  chapter 
has  been  arranged  alphabetically.  In  studying  the  reactions  of 
the  common  elements,  however,  it  may  be  recommended  to  take 
them  up  in  the  following  order,  which  has  been  chosen  partly 
according  to  Mendeleeff's  periodic  system  of  the  elements,  and 
partly  to  bring  together  some  of  the  elements  which  exhibit  simi- 
larities in  their  analytical  reactions  :* 

1.  Hydrogen,  p.  81.     4.  Potassium,  p.  105.      7.  Strontium,  p.  116.      10.  Zinc,    p.  130. 

2.  Lithium,          90.     5.  Magnesium,       91.      8.  Barium,  52.      11.  Copper,      71. 
3    Sodium,          115.     6.  Calcium,           58.      9.  Aluminium,       42.      12.  Silver,       113. 

*  In  the  descriptions  of  tests  and  experiments,  sizes  and  distances  will  be  (riven 
in  millimeters  and  centimeters  ;  quantities  of  powders  and  dry  reagents  in  terras  of 
the  ivory  spoon;  and  the  volume  of  liquids  in  cubic  centimeters. 

Inch  Scale. 


,  I  ,  1 

I 

2 

I 

I 

3 
I 

Centimeter  Scale. 


^ 

2 

3 

4 

5 

€ 

7 

Illl 

8 

III! 

-15 


•W 


FIG.  42. — Inch  and  centimeter  scales,  ivory  spoon,  and  end  of  a  test-tube  with  cubio 
centimeters  indicated  upon  it.     All  natural  size. 

41 


42  REACTIONS   OF   THE   ELEMENTS.  Aluminium 

13.  Lead,       p.  87.  18.  Cobalt,    p.  71.  23.  Chlorine,      p.  67.  28.  Bismuth,  p.  54. 

14.  Mercury,       93.  19.  Nickel,         96.  24.  Boron,  56.  29.  Carbon,          61. 

15.  Chromium,  69.  20.  Oxygen,     100.  25.  Phosphorus,   101.  30.  Silicon,         107. 

16.  Manganese,  98.  21.  Sulphur,    118.  26.  Arsenic,  ^7.  31.  Titanium,     187. 

17.  Iron,  83.  22.  Fluorine,     75.  27.  Antimony,        43.  32.  Tin,  725. 

Aluminium,  Al. — Trivalent.     Atomic  weight,  27. 

OCCURRENCE. — Next  to  oxygen  and  silicon,  aluminium  is  prob- 
ably the  most  abundant  element  in  the  crust  of  the  earth  (p.  3). 
It  is  a  metallic  element,  occurring  most  frequently  in  the  group  ot 
silicates,  while  it  is  also  found  in  a  number  of  oxides,  fluorides, 
phosphates,  and  sulphates,  Kaolinite,  H4Al2Si209 ;  cyanite, 
Al2SiO6 ;  orthoclase,  KAlSi3O8  •  almandine  garnet,  Fe3Al2(SiO4)3 ; 
corundum,  ALO, ;  and  cryolite,  ]STa3AlF6 ,  may  serve  as  examples  of 
its  compounds.  Aluminium  also  plays  the  part  of  a  weak  acid, 
and  by  some  authors,  spinel,  MgAl2O4  =  MgO.Al2O3,  and  a  few 
similar  compounds  are  regarded  as  aluminates.  Aluminium  is  a 
constituent  of  most  rocks,  almost  the  only  exceptions  being  the 
carbonates,  sandstones,  and  quartzites. 

DETECTION. — Igniting  with  cobalt  nitrate  is  the  only  satisfac- 
tory blowpipe  test  for  aluminium.  For  a  test  in  the  wet  way, 
precipitation  with  ammonia  is  recommended, 

1.  Test  with    Cobalt  Nitrate. — Infusible  minerals  containing 
aluminium,  if  moistened  with  cobalt  nitrate  and  intensely  ignited 
before  the  blowpipe,  assume  a  fine  blue  color.     Cobalt  nitrate  on 
ignition  yields  cobalt  oxide,  CoO,  which  is  black,  and  this  oxide 
unites  in  some  inexplicable  way  with  the  alumina  to  give  the 
characteristic  blue  color.     In  applying  the  test  to  very  hard  min- 
erals it  is  best  to  powder  them,  then  moisten  with  cobalt  nitrate 
and  heat  either  on  charcoal  or  on  a  small  loop  on  platinum  wire. 
The  test  is  restricted  to  compounds  which  are  light  colored,  or 
become  so  on  ignition,  and  is  not  characteristic  if  applied  to  fusible 
minerals,  as  cobalt  oxide  may  impart  a  blue  color  to  any  fused 
material  or  flux.     Zinc  silicates  also  give  a  blue  color,  p.  133. 

Apply  this  test  to  fragments  of  cyanite,  Al2Si06 ,  held  in  the  forceps, 
and  to  finely  powdered  corundum,  Al.,0,. 

2.  Precipitation  with  Ammonia. — Ammonia,  when  added  in 


Antimony  REACTIONS   OF   THE   ELEMENTS.  43 

slight  excess  to  an  acid  solution  containing  aluminium,  precipi- 
tates gelatinous  aluminium  hydroxide,  A1(OH)3.  A  great  many 
other  substances  yield,  with  ammonia,  gelatinous  precipitates 
resembling  aluminium  hydroxide,  and  therefore  it  is  necessary  to 
make  the  following  additional  tests :  Collect  the  precipitate 
on  a  filter-paper,  wash  with  water,  transfer  some  of  it  to  a  test- 
tube,  and  add  potassium  hydroxide,  when  the  precipitate,  if  it  is 
aluminium  hydroxide,  will  go  easily  and  completely  into  solution. 
Burn  the  paper  containing  the  precipitate  in  a  porcelain  crucible 
(Fig.  27,  p.  22),  and  test  the  residue  with  cobalt  nitrate. 

Dissolve  an  ivory  spoonful  of  alum,  KAl(S04)a.12HaO,  in  a  test-tube 
in  5  cc.  of  hot  water,  add  2  cc.  of  hydrochloric  acid,  and  then  ammonia  in 
slight  excess;  that  is,  until  a  distinct  odor  of  ammonia  is  perceptible  after 
the  contents  of  the  tube  have  been  thoroughly  mixed.  Filter  off  the  pre- 
cipitate, and  test  as  recommended  above. 

3.  For  detecting  aluminium  in  insoluble  silicates,  where  the 
above  methods  .cannot  be  directly  applied,  see  p.  110,  §  4. 

Ammonium,  NH4. — Univalent.     Molecular  weight,  18. 

OCCURRENCE.  — The  radical  ammonium,  NH4 ,  plays  the  part  of 
a  metal,  and  in  its  chemical  relations  is  very  similar  to  potassium. 
Minerals  containing  ammonium  are  of  rather  rare  occurrence,  and 
are  generally  soluble  in  water.  Sal  ammoniac,  NH4C1,  and  struv- 
ite,  NH4MgPO4.6H2O,  are  examples  of  its  compounds. 

DETECTION. — Compounds  containing  ammonium,  when  boiled 
with  a  solution  of  potassium  hydroxide,  or  heated  in  a  closed  tube 
with  lime  (ignited  calcite),  yield  the  strong  and  very  characteristic 
odor  of  ammonia. 

Antimony,  Sb. — Trivalent  and  pentavalent.  Atomic  weight, 
120. 

OCCURRENCE. — Antimony  is  found  chiefly  in  combination  with 
sulphur,  either  as  stibnite,  Sb2S3,  or  as  sulphantimonites,  which 
are  salts  of  sulpTiantimonious  acids,  H2Sb2S4,  H4Sb2S5,  H6SbaS6, 
H8Sb2S7,  etc.  The  composition  of  the  sulphantimonites  is  fre- 
quently expressed  as  a  combination  of  Sb2S3  with  sulphides  of 


44  REACTIONS   OF   THE    ELEMENTS.  Antimony 

the  metals,  examples  being,  —  zinkenite,  PbSb2S4  =  PbS.Sb2S3 ; 
jamesonite,  Pb2Sb2S6  =  2PbS.Sb2S, ;  pyrargyrite,  Ag8SbSs  = 
3AgaS.Sb3S3;  and  tetrahedrite,  CueSbaS7  =  4Cu2S.Sb2Ss.  (See  also 
the  sulpharsenites  (p.  47),  with  which  the  sulphantimonites  are 
frequently  isomorphous.)  Antimony  also  occurs  native,  rarely  in 
combination  with  metals  as  antimonides,  breithauptite,  NiSb,  and 
occasionally  in  different  combinations  with  oxygen,  senarmontite, 
Sba08 ,  and  cervantite,  Sb2O4. 

DETECTION. — Antimony  may  usually  be  detected  by  the  coat- 
ing of  oxide  formed  by  roasting  on  charcoal  or  in  the  open  tube. 
The  closed-tube  reaction  is  also  recommended  for  sulphide  of 
antimony. 

1.  Roasting  on  Charcoal:  Coating  of  Oxide. — Most  anti- 
mony compounds,  when  heated  on  charcoal  in  the  oxidizing  flame, 
yield  a  dense  white  sublimate  of  oxide  of  antimony,  which  de- 
posits quite  near  the  heated  part  (compare  Arsenic),  and  appears 
bluish  if  the  coating  is  thin,  so  that  the  black  of  the  charcoal 
shows  through  it.  The  coating  is  due  to  volatilization  of  the 
antimony  and  its  oxidation  in  passing  into  the  air.  It  is  quite 
volatile  when  heated  before  the  blowpipe  either  in  the  oxidizing 
or  reducing  flames,  and  may  be  driven  about  and  made  to  change 
its  place  on  the  charcoal.  The  fumes  have  no  distinctive  odor 
(difference  from  arsenic).  In  the  absence  of  other  elements  which 
give  coatings  on  charcoal,  this  test  serves  as  a  very  simple  and 
characteristic  one  for  the  detection  of  antimony.  Where  other 
elements  (especially  lead  and  bismuth)  interfere,  the  open-tube 
reaction  will  give  confirmatory  and  decisive  results. 

Some  oxides  of  antimony  are  not  volatile  in  the  oxidizing 
flame,  and  when  these  are  to  be  tested  it  is  necessary  to  heat  them 
in  a  reducing  flame  to  convert  the  antimony  to  the  metallic  state, 
so  that  it  will  volatilize  and  give  the  coatirg  of  oxide  described 
above. 

Test  the  foregoing  with  stibnite,  Sb2S3.     Place  about  \  ivory  spoonful  of 
it  on  a  flat  charcoal  surface,  and  heat  with  a  small  oxidizing  flame  (]).  40, 
.  41)  until  the  material  is  completely  volatilized.     Note  that  the  sublimate 


Antimony  REACTIONS    OF   THE    ELEMENTS.  45 

deposits  close  to  the  heated  part  (difference  from  arsenic),  and  test  its 
volatility  in  both  the  oxidizing  and  reducing  flames.  The  odor  which  may 
he  observed  is  due,  not  to  the  antimony,  but  to  sulphur  (p.  119,  §  2). 

2.  Roasting  in  tlie  Open  Tube:  Sublimate  of  Oxide. — When 
metallic  antimony  and  its  compounds  with  sulphur  are  heated  in 
the  open  tube,  oxides  of  antimony  are  formed  and  deposit  as  sub- 
limates on  the  walls  of  the  tube,  but  the  products  vary  somewhat 
with  the   conditions.     If  sulphur  is  present,  the   oxide  usually 
appears  as  a  dense  white   smoke,    and  most  of  it  settles  for  a 
considerable  distance  along  the  under  side  of  the  tube,  while  some 
of  it  condenses  as  a  ring  rather  near  the  heated  part.     The  ring  is 
Sb2O3 ,  and  when  examined  with  a  lens  will  frequently  be  found  to 
consist  of  two  kinds  of  crystals,  octahedrons  and  prisms,  corre- 
sponding  to  senarmontite    and  valentinite,  two  forms  of  Sb203 
found  in  nature.     When  heated,  this  part  of  the  sublimate  is 
completely  volatile,  and  may  be  driven  up  and  out  of  the  tube, 
although  much  more  slowly  than  oxide  of  arsenic.     The  white 
sublimate  which  condenses  along  the  bottom  of  the  tube  is  prob- 
ably   antimonate  of    antimony,   SbSb04.     It  is    non-volatile,    in- 
fusible, and  becomes   straw-yellow  when   hot,    but  white  again 
when  cold.     In  the  absence  of  sulphur  and  in  some  compounds 
containing  it  (apparently  those  that  oxidize  slowly),  only  the  vol- 
atile Sb2O3  forms.     Just  why  the  presence  of  sulphur  causes  the 
formation  of  the  higher  oxide  is  not  known,   but  probably  its 
oxide  acts  in  some  way  as  a  means  for  transferring  oxygen, 
changing  Sb2O3  to  Sb204. 

Test  the  above  with  stibnite,  Sb2S3 ,  using  about  |  of  an  ivory  spoonful, 
and  heating  very  carefully,  as  directed  on  p.  19.  Test  also  the  volatility 
of  the  sublimate,  and  compare  the  reaction  carefully  with  the  correspond- 
ing one  for  arsenic  (p.  48,  §  2).  To  obtain  the  wholly  volatile  sublimate 
of  Sb20n ,  heat  a  little  metallic  antimony  in  the  open  tube. 

3.  Heating  in  the  Closed   Tube.— Sulphide  of  antimony  and 
many  sulphantimonites,  when  heated  in  a  closed  tube,  yield  a 
characteristic  looking   sublimate   of    oxy sulphide  of    antimony, 


46  REACTIONS   OF  THE   ELEMENTS.  Antimony 

Sb2SaO.  This  requires  "a  rather  intense  heat  for  its  production. 
It  is  volatilized  with  difficulty,  and  appears  black  when  hot,  but 
changes  on  cooling  to  a  rich  reddish-brown. 

Metallic  antimony  cannot  be  volatilized  in  a  closed  glass  tube, 
except  at  a  very  high  temperature,  where  hard  glass  softens. 
Owing  to  this  behavior,  arsenic  and  antimony,  which  frequently 
occur  together,  especially  in  sulpharsenites  and  sulphantimonites, 
may  sometimes  be  conveniently  separated  and  identified,  since 
arsenic  and  its  sulphides  volatilize  readily.  After  driving  the 
sublimate  a  short  way  up  the  tube,  cut  off  the  latter  a  little  below 
it,  and  test  for  the  arsenic  by  the  open- tube  method  (p.  48,  §  2). 
After  removing  the  residue  from  the  tube,  test  it  for  antimony, 
either  before  the  blowpipe  on  charcoal,  or  in  the  open  tube.  To 
test  for  arsenic  in  presence  of  antimony,  see  also  p.  49,  §  4. 

Take  a  small  fragment  of  stibnite  in  a  closed  tube,  and  heat  it  at  a  high 
temperature  and  for  a  considerable  time.  The  small, quantity  of  air  in  the 
tube  is  all  that  is  necessary  to  bring  about  the  reaction  shown  by  the 
following  equation:  Sb2S3  -j-  0  —  Sb2S20  +  S.  A  slight  ring  of  sulphur 
deposits  beyond  the  antimony  sublimate.  This  is  one  of  the  few  closed- 
tube  reactions  where  the  air  in  the  tube  plays  an  important  part. 

4.  Test  with  Hydriodic  Acid  on  a  Gypsum  Tablet. — Antimony 
compounds,  when  treated  according  to  directions  given  on  p.  17, 
yield  a  beautiful  red  coating  of  iodide  of  antimony,  which  disap- 
pears when  held  over  strong  ammonia. 

5.  Flame  Test. — When,  antimony  compounds  are  heated  before 
the  blowpipe  in  the  reducing  flame,  antimony  volatilizes  and  im- 
parts to  the  flame  a  pale  greenish  color.     The  precautions  against 
alloying  the  forceps,  mentioned  on  p.  15,  should  be  observed. 

6.  Oxidation  with  Nitric  Acid. — When  antimony  or  its  sul- 
phides are  treated  with  concentrated  nitric  acid,  the  antimony  is 
oxidized  to  metantimonic  acid,  SbO2OH  (?),  which  is  a  white  sub- 
stance, very  insoluble  in  water  and  in  nitric  acid.     By  diluting 
with  water  and  filtering,  quite  a  satisfactory  separation  of  anti- 
mony may  be  obtained  from  other  substances  with  which  it  is  apt 
to  occur  in  combination.     The  material  on  the  filter-paper  may  be 


Arsenic.  REACTIONS   OF   THE   ELEMENTS.  47 

examined  for  antimony  by  heating  before  the  blowpipe  on  char- 
coal, and  the  different  metals  in  the  filtrate  may  be  precipitated  by 
appropriate  reagents.  This  treatment  will  frequently  be  found 
convenient,  especially  for  detecting  a  small  quantity  of  antimony 
in  pres*7  ice  of  arsenic. 

Arsenic,  As. — Trivalent  and  pentavalent.     Atomic  weight,  75. 

OCCURRENCE. — Arsenic  usually  plays  the  part  of  a  non-metallic 
element,  and  forms  three  important  classes  of  compounds, — the 
arsenides,  the  sulpharsenites,  and  the  arsenates.  In  arsenides, 
the  metals  are  united  directly  with  arsenic  ;  as  nicolite,  NiAs,  and 
smaltite,  CoAsa.  These  compounds  are  analogous  to  the  sulphides 
and  are  often  isomorphous  with  them.  Several  compounds  are 
known  which  are  combinations  of  arsenide  and  sulphide ;  as 
the  commonest  of  the  arsenic  minerals,  arsenopyrite,  FeAsS  = 
FeAs,  +  FeS2.  The  sulpharsenites  may  be  regarded  as  salts 
of  sulpharsenious  acids,  H3As2S4,  H4As2S6,  H,As3S6,  H8As2S7, 
etc.  Examples  of  these  compounds  are  sartorite,  PbAsaS4  = 
PbS.As3Sb;  dufrenoysite,  Pb3As2S6=2PbS.As3S3;  proustite,  Ag3AsS, 
=  3Ag2S.AsaS3;  and  tennantite,  Cu8As3S7  — 4Cu3S.As2S3.  The  num- 
ber of  Sulphantimonites,  is  quite  large,  but  they  are  of  rather 
rare  occurrence  (compare  sulphantimonites,  p.  43).  Enargite, 
Cu3AsS4  =  3Cu2S.  As2S%5,  is  a  sulphar senate  or  salt  of  sulphar  senic 
acid,  HsAsS4,  but  other  salts  of  this  acid  are  exceedingly  rare. 
The  arsenates,  salts  of  arsenic  acid,  H8AsO4 ,  are  analogous  to 
the  phosphates,  and  although  a  great  many  of  them  are  known, 
they  are  of  rather  rare  occurrence.  Examples  are  mimetite, 
Pb4(PbCl)(PO4)8;  olivenite,  Cu(CuOH)AsO4 ;  and  scorodite,  FeAsO4. 
2H2O.  In  addition  to  the  foregoing  classes  of  compounds,  the  ele- 
ment occurs  as  native  arsenic,  as  the  sulphides,  realgar,  AsS,  and 
orpiment,  As2S3 ,  and  sparingly  as  the  oxide,  As2O3. 

DETECTION. — The  method  that  should  be  used  for  the  detec- 
tion of  arsenic  depends  upon  whether  or  not  the  mineral  contains 
oxygen.  With  those  compounds  containing  no  oxygen,  it  is  best 
to  employ  an  oxv  ition  process,  such  as  roasting  on  charcoal  ©r  in 


48  BEACTIONS   OF   THE   ELEMENTS.  Arsenic 

the  open  tube.  Heating  in  a  closed  tube  is  a  good  method  for 
some  compounds.  With  arsenates  it  is  necessary  to  employ  a 
reduction  process. 

Tests  for  Arsenic  in  Minerals  containing  No  Oxygen. 

1.  Roasting  on  Charcoal :  Coating  of  Oxide :  Arsenical  Odor. — 
When  arsenic,  its  sulphide,  or  an  arsenide,  is  heated  before  the 
blowpipe  on  charcoal,  volatile  products   are  given  off,   and  the 
arsenic  unites  with  the  oxygen  of  the  air  to  form  As2O3 ,  a  white, 
volatile  substance,  which  condenses  on  the  charcoal  at  a  consid- 
erable distance  from  the  assay.     The  fumes  that  are  given  off 
when  the  assay  is  heated  in  the  reducing  flame  have  a  disagree- 
able, garlic-like  odor  with  which  one  soon  becomes  familiar,  and 
which  serves  as  a  characteristic  test  for  the  identification  of  the 
element.     The  odor  is  perhaps  due  to  the  formation  of  a  little 
arseniuretted  hydrogen,  AsH3.     It  does  not  come  from  As2Os,  for 
this,  when  volatilized  without  reduction,  gives  no  odor. 

The  tests  mentioned  above  may  be  very  well  observed  by  heating  either 
the  powder  or  fragments  of  arsenopyrite,  FeAsS,  on  a  flat  charcoal  surface. 
Note  carefully  that  the  sublimate  deposits  at  a  considerable  distance  from 
the  assay,  and  test  its  volatility  by  heating  with  a  blowpipe  flame  (com- 
pare Antimony,  p.  44,  §1).  In  addition  to  the  garlic  odor  of  the  arsenic, 
the  sulphur,  especially  after  the  assay  has  been  heated  for  some  time,  yields 
a  strong  pungent  odor  of  S02  (p.  119,  §  2),  which  is  entirely  different  from 
that  of  the  arsenic,  and  must  not  be  mistaken  for  it. 

2.  Roasting  in  the  Open  Tube.—  When  arsenic,  an  arsenide,  or 
a  sulphide  of  arsenic,  is  heated  in  an  open  tube,  a  sublimate  of 
white  crystalline  arsenious  oxide,  AsaO3 ,  is  formed,  and  condenses 
as  a  ring  on  the  sides  of  the  glass.     The  sublimate  is  further  char- 
acterized by  being  volatile,  so  that  it  can  be  readily  driven  up  and 
out  of  the  tube  by  heating.     The  crystals  of  As2O3  develop  best 
where  the  glass  is  rather  warm,  and  by  breaking  the  tube  and 
examining  them  with  a  microscope  it  will  be  found  that  they  are 
usually  simple,  but  occasionally  twinned,  octahedrons. 

Heat  from  ^  to  -fa  of,  an  ivory  spoonful  of  powdered  arsenopyrite, 
FeAsS,  in  an  open  tube,  and  observe  the  reactions  mentioned  above. 


Arsenic  [REACTIONS   OF   THE   ELEMENTS.  49 

SFeAsS  +  10  0  =  Fe203  +  2S02  +  As203.  If  a  yellow  deposit  of  sulphide 
of  arsenic  forms,  or  a  black  one  of  arsenic,  it  indicates  that  the  oxidation 
has  not  been  made  properly;  either  the  substance  was  heated  too  rapidly. 
or  there  was  not  a  sufficient  draft  of  air  passing  up  the  tube  to  bring  about 
the  oxidation  (see  p.  19). 

3.  Heating   in   the  Closed  Tube :   Arsenical  Mirror. — When 
arsenic  and  some  arsenides  are  heated  in  the  closed  tube,  arsenic 
volatilizes  and  condenses  on  the  cold  walls  of  the  tube.     When 
very  little  deposits,  the  sublimate  appears  brilliant  black  (arseni- 
cal mirror) ;  but  if  much  of  it  is  driven  off,  that  which  is  nearest 
to  the  heated  end  crystallizes  and  appears  gray.     If  the  tube  is 
broken  just  below  the  sublimate  and  heated  so  that  the  arsenic 
volatilizes,  the  characteristic   garlic  odor  may  be  observed  very 
distinctly,  perhaps  better  in  this  way  than  in  any  other,  and  a 
very  little  arsenic  is  sufficient  to  give  it. 

Test  the  above  with  arsenopyrite,  FeAsS.  At  first,  perhaps,  a  little 
yellow  sulphide  of  arsenic  may  be  driven  off,  but  the  arsenical  mirror  soon 
makes  its  appearance.  Owing  to  the  greater  affinity  of  iron  for  sulphur 
than  for  arsenic,  the  change  which  the  mineral  undergoes  is  essentially  as 
follows  :  FeAsS  =  FeS  -r  As. 

The  sulphides  of  arsenic,  realgar,  AsS,  and  orpiment,  As2S3,  when 
heated  in  the  closed  tube,  are  completely  volatilized,  condensing  at  first  as 
a  reddish-yellow  sublimate,  changing  to  dark  red  or  almost  black  when  hot, 
and  to  reddish-yellow  when  cold. 

4.  Special  Test  for  Oxide  of  Arsenic. — An  exceedingly  deli- 
cate test,  proposed  by  Berzelius,  may  be  made  by  placing  a  little 
oxide  of  arsenic  at  the  bottom  of  a  closed  tube  drawn  out  as  in 
Fig.  43,  and  above  it,  a  splinter  of 

charcoal.       Heat  is  first  applied  at 

the  upper  end  of  the  charcoal,  until  FlG-  43- 

the  latter  becomes  red  hot,  and   then  at   the   lower  end,  when 

the  oxide  of  arsenic  volatilizes,  becomes  reduced  in  passing  the 

red-hot  charcoal,    and   condenses   above  as  an  arsenical  mirror. 

This  method  will  be  found  very  convenient  for  testing  coatings  of 

oxides,  obtained  by  heating  before  the  blowpipe  on  charcoal,  when 

there  is  any  doubt  as  to  whether  they  contain  arsenious  oxide. 


50  REACTIONS   OF  THE   ELEMENTS.  Arsenic 

It  will  also  be  especially  useful  when  it  is  desired  to  detect 
arsenic  in  the  presence  of  antimony,  for  the  two  elements 
frequently  occur  together,  and  both  give  volatile  white  coatings  on 
charcoal,  but  antimony  oxide  gives  no  mirror  when  treated  as 
above.  It  is  to  be  noted,  however,  that  when  a  considerable 
quantity  of  antimony  is  taken,  a  trifling  dark  deposit  of  some 
antimony  compound  may  form  near  the  charcoal,  but  this 
should  not  be  mistaken  for  the  characteristic  arsenical  mirror, 
which  forms  a  considerable  distance  up  the  tube.  In  order  to 
make  the  test,  it  is  only  necessary  to  scrape  up  a  little  of  the 
coating  which  is  farthest  away  from  the  assay  (a  little  charcoal 
powder  with  it  does  no  harm),  and  heat  in  the  tube  as  directed 
above. 

5.  Test  with  Hydriodic  Acid  on  a  Gypsum  Tablet. — Arsenic 
compounds,  when  treated  according  to  directions  given  on  p.  17, 
yield  a  very  volatile  orange  to  yellow  coating  of  iodide  of  arsenic. 

6.  Flame  Test. — If  arsenic  is  volatilized  from  a  mineral  by  heat- 
ing before  the  blowpipe  in  the  reducing  flame,  it  imparts  to  the 
latter  a  violet  tinge.      The  color  may  also  be  obtained  when  either 
arsenic  or  its  sublimate  of  oxide  in  a  tube  is  volatilized,  so  that  it 
passes  from  the  end  of  the  tube  into  the   reducing  part  of  a 
Bunsen-burner  flame. 

7.  Oxidation  with  Nitric  Acid. — Compounds  of  arsenic,  when 
boiled  with  concentrated  nitric  acid,  are,  with  few  exceptions, 
oxidized  and  dissolved,  with  formation  of  arsenic  acid,  H3As04. 
To  detect  arsenic  in  the  solution,  the  methods  given  beyond  under 
ar senates  (§  9,  b)  may  be  employed. 

ARSENATES. 

DETECTION. — The  reduction  of  arsenates  in  the  closed  tube, 
with  the  formation  of  an  arsenical  mirror,  furnishes  the  best 
means  of  detection.  The  oxidation  and  roasting  processes  used 
for  the  detection  of  arsenic  in  arsenides  and  other  compounds 
containing  no  oxygen  cannot  be  applied  to  arsenates,  as  they  are 
already  oxidized. 


Arsenic  REACTIONS   OF   THE    ELEMENTS.  51 

1.  Reduction  in  the  Closed  Tube :  Arsenical  Mirror. — a.  With 
few  exceptions  the  arsenates  are  readily  fusible,  and  for  all  such 
the  following  decisive  test  may  be  applied :  In  a  narrow  closed 
tube  place  a  few  splinters  of  charcoal  and  a  fragment  of  the 
arsenate,  and  heat  intensely  with  a  blowpipe  flame,  so  that  the 
fused  mineral  comes  in  contact  with  the  charcoal.  Under  these 
conditions  the  arsenate  is  reduced,  and  the  arsenic  volatilizes  and 
forms  an  arsenical  mirror. 

b.  Provided  the  arsenate  is  infusible  in  the  closed  tube,  and  in 
the  absence  of  easily  reducible  metals,  such  as  lead,   copper,  or 
iron,   proceed  as  follows :    Mix   a  little   of  the  finely  powdered 
mineral  with  4  volumes  of  dry  sodium  carbonate   and  a  little 
powdered  charcoal,  transfer  to  a  closed  tube,  warm  gently  at  first, 
and   then  heat  intensely  in  a  Bunsen-burner  or  blowpipe  flame. 
Under  these  conditions  the    arsenic,  resulting  from  the  reducing 
action  of  the  charcoal,  will  volatilize  and  condense  on  the  glass  as 
an  arsenical  mirror. 

c.  When  the  foregoing  tests  cannot  be  applied,  mix  the  pow- 
dered mineral  with  about  6  volumes  of  sodium  carbonate,  and  fuse 
either  in  a  platinum  spoon  or  on  a  flat  charcoal  surface,  using  an 
oxidizing  flame.     The  fused  material  is  transferred  to  a  test-tube, 
boiled  for  a  minute  with  about  5  cc.  of  water,  in  order  to  dissolve 
the  sodium  arsenate  resulting  from  the  fusion,  and  then  filtered. 
To  the  filtrate  hydrochloric  acid  is  added  in  excess,  then  an  excess 
of  ammonia,  which  may  cause  the  precipitation  of  some  arsenate, 
and  lastly  a  little  magnesium  sulphate  solution,  in  order  to  precip- 
itate the  arsenic  as  ammonium  magnesium  arsenate,  NH4MgAs04. 
Filter  off  the  precipitate,   dry  it  by  pressing  between  blotting- 
paper,  mix   a  little   of  it   with   sodium  carbonate  and  charcoal 
powder,  and  heat  in  a  closed  tube  as  directed  in  §  5.     Provided 
the  precipitate  is  small,  place  the  filter-paper  containing  it  in  a 
porcelain   crucible,  char  the  paper  by  very  gentle  ignition,  and 
test  the  charred  material,  mixed  with  a  little  sodium  carbonate  and 
charcoal  powder,  in  a  closed  tube. 


52  REACTIONS   OF  THE   ELEMENTS.  Barium 

Barium,  Ba. — Bivalent.     Atomic  weight,  137. 

OCCURRENCE. — Barium  is  an  alkali-earth  metal,  which  is  found 
quite  abundantly  in  barite,  BaSO4,  and  in  some  regions  in 
witherite,  BaCO3 ,  but  other  combinations  containing  it  are 
seldom  met  with.  It  occurs  in  only  a  few  silicates  (hyalophane, 
harmotome,  brewsterite),  and  sparingly  in  the  igneous  rocks  o( 
some  regions. 

DETECTION. — Usually  barium  may  be  readily  detected  by  the 
flame  coloration,  alkaline  reaction,  and  precipitation  as  barium 
sulphate. 

1.  Flame  Test. — Barium  gives  a  yellowish-green  coloration  to 
the  flame,  which  may  sometimes  be  intensified  by  moistening  the 
assay  with  hydrochloric   acid.     The  color    cannot    be  obtained 
directly  from  silicates,  and  must  not  be  mistaken  for  that  of  boron 
and  phosphorus. 

Make  the  experiment  with  barite  or  witherite,  holding  fragments  in  the 
forceps  and  heating  before  the  blowpipe.  Make  the  test  also  by  heating 
some  of  the  powder  on  a  platinum  wire,  as  directed  on  p.  35. 

2.  Alkaline  Reaction. — With  the  exception  of  the  silicates 
and  phosphates,  barium  minerals  become  alkaline  upon  intense 
ignition  before  the  blowpipe.     A  similar  reaction  is  obtained  with 
other  minerals  containing  alkalies  and  alkaline  earths. 

Heat  fragments  of  barite  or  witherite,  and  place  them  upon  moistened 
turmeric-paper.  For  the  cause  of  the  alkaline  reaction,  see  Calcium 
(p.  58,  §  1). 

3.  Precipitation  as   Barium    Sulpliate.  —  Barium    sulphate, 
BaS00  is  very  insoluble  in  water  and  dilute  acids,  and  will  be  pre- 
cipitated, therefore,  from  solutions  containing  barium,  upon  the 
addition  of  a  few  drops  of  dilute  sulphuric  acid.     The  test  is  a 
very  delicate  one,  and  will  always  serve  to  distinguish  compounds 
containing  barium  from  those  containing  boron  and  phosphorus, 
which  may  give  green  flame  colorations.     It  will  also  serve  for  the 
detection  of  barium  in'  silicates  and  other  compounds. 


Beryllium  REACTIONS   OF   THE   ELEMENTS.  53 

a.  Dissolve   £   ivory  spoonful   of  witherite    in  3  cc.  of  dilute   hydro- 
chloric acid,  warm  if  necessary,  dilute  with  from  10  to  15  cc.  of  water,  and 
add  dilute  sulphuric  acid,  when  a  white  precipitate  will  form,  which  is 
barium  sulphate.     This  should  be  collected  on  a  filter-paper,  washed  with 
water,  and  tested  on  platinum  wire,  as  directed  under  §  1. 

b.  To  apply  this  test  to  silicates,  dissolve  in  hydrochloric  acid    (after 
previous  fusion  with  sodium  carbonate,  if  the  mineral  should  happen  to  be 
insoluble,  see  p.  110,  §  4),  separate  the  silica,  precipitate  barium  sulphate 
with  sulphuric  acid,  collect   on  a  small  filter,  arid  make  a  flame  test  on 
platinum  wire.     If  both  barium  and  strontium  are  present,  a  mixed  flame 
will  be  obtained,  and,  after  moistening  with  hydrochloric  acid,  often  the 
red  of  strontium  will   appear  strongest  at  first,  while  later  the  green  of 
barium  may  be  seen.     In  order  to  obtain  decisive  results,  it  may  be  necessary 
to  make  use  of  a  spectroscope. 

4.  Specific  Gravity. — On  account  of  the  high  atomic  weight  of 
barium,  minerals  containing  it  are  characterized  by  high  specific 
gravities,  considerably  greater  than  those  of  the  corresponding 
strontium  or  calcium  compounds  (see  p.  118,  §  4). 

Beryllium,  Be. — Bivalent.     Atomic  weight,  9. 

OCCURRENCE. — Although  usually  regarded  as  a  rare  element,  beryllium, 
sometimes  called  glucinum,  Gl,  is  found  in  the  common  mineral  beryl, 
Be3Ala(Si03)6,  and  in  a  number  of  others  which  are  not  very  rare;  as 
chrysoberyl,  phenacite,  leucophanite,  helvite,  euclase,  gadolinite,  beryllonite, 
and  herderite. 

DETECTION. — There  are  no  satisfactory  blowpipe  reactions  for  beryllium, 
and  tests  must  be  made,  therefore,  in  the  wet  way,  which  requires  some 
skill  in  manipulation. 

a.  If  the  mineral  is  a  silicate,  treat  it  according  to  directions  given  on 
p.  110 ,  §  4,  for  the  solution  of  the  mineral  and  separation  of  silicic  acid; 
then  heat  the  filtrate  from  the  silica  to  boiling,  and  precipitate  the  beryllium 
with  ammonia,  which  will  also  cause  precipitation  of  iron,  aluminium, 
and  possibly  other  elements,  if  present.  Ammonia  precipitates  beryllium 
hydroxide,  which  resembles  aluminium  hydroxide  in  appearance.  This  is 
filtered  and  washed  well  with  water,  transferred  together  with  the  paper 
to  some  vessel,  and  warmed  with  dilute  hydrochloric  acid  in  order  to  dis- 
solve it.  The  paper  is  filtered  off,  and  the  filtrate  evaporated  carefully 
(best  in  a  casserole)  until  only  a  drop  or  two  of  the  acid  is  left.  After  cool- 
ing, a  few  drops  of  water  are  added  to  obtain  everything  in  solution,  and 
then  a  little  potassium  hydroxide  solution,  a  drop  at  a  time,  and  just  suffi- 
cient to  dissolve  the  precipitate  of  beryllium  hydroxide  which  forms  at 


54  REACTIONS   OF  THE   ELEMENTS.  Bismuth 

first.  The  solution  is  then  diluted  with  cold  water  to  a  volume  of  at  least 
50  cc.,  any  precipitate  of  ferric  hydroxide  or  other  material  filtered  off, 
and  the  filtrate  boiled  for  a  short  time,  when,  if  beryllium  is  present,  a  pre- 
cipitate of  beryllium  hydroxide  will  appear.  The  precipitate,  if  collected 
on  a  filter-paper  and  ignited,  yields  beryllium  oxide,  and  this  when  ignited 
with  cobalt  nitrate  assumes  a  not  very  decisive  lavender  color. 

b.  If  the  mineral  is  a  phosphate,  special  treatment  is  needed.  The 
powdered  mineral  is  dissolved  in  hydrochloric  acid  (after  fusion  with 
sodium  carbonate,  if  necessary);  when  cold,  ammonia  is  added  until  a  per- 
manent precipitate  forms,  and  then  hydrochloric  acid,  a  drop  at  a  time, 
until  the  solution  becomes  clear.  To  the  now  nearly  neutral,  cold,  and  not 
too  concentrated  solution,  sodium  acetate  is  added,  and  the  precipitated 
beryllium  phosphate,  which  may  also  contain  ferric  and  aluminium  phos- 
phates, is  filtered  and  washed.  The  precipitate  is  next  ignited  in  a  crucible 
until  the  carbon  of  the  paper  is  destroyed,  and  is  then  fused  in  platinum 
with  sodium  carbonate,  by  which  treatment  sodium  phosphate  and  beryllium 
oxide  are  formed.  The  fusion  is  then  treated  with  hot  water  to  dissolve 
the  sodium  phosphate,  the  beryllium  oxide  is  collected  on  a  filter-paper  and 
washed,  and  it  is  afterwards  dissolved  in  hydrochloric  acid  and  tested  with 
potassium  hydroxide,  as  described  under  a.  If  it  is  known  that  the 
alkali-earth  metals  are  absent,  the  mineral  may  be  fused  directly  with 
sodium  carbonate,  and  treated  like  the  above  sodium  carbonate  fusion. 

Bismuth,  Bi. — Trivalent.     Atomic  weight,  208. 

OCCURRENCE. — Bismuth  plays  the  part  of  a  weak  basic  element 
and  also  that  of  an  acid-forming  one,  and  is  of  rather  rare  occur- 
rence in  minerals.  It  is  found  native  and  as  sulphide,  selenide, 
telluride,  oxide,  silicate,  and  carbonate.  The  combinations  of  its 
sulphide  with  sulphides  of  the  metals,  the  sulpJiobismutliites,  are 
analogous  to  the  sulphantimonites  and  sulpharsenites, 

DETECTION.— Usually  bismuth  may  be  readily  detected  by  its 
reactions  on  charcoal  and  by  the  iodine  tests. 

I.  deduction  on  Char  coal  to  Metallic  Bismuth,  and  Formation 
of  a  Coating  of  Bismuth  Oxide.—  Usually  bismuth  can  be  readily 
reduced  from  its  compounds  by  mixing  £  ivory  spoonful  of  the 
powdered  mineral  with  about  3  volumes  of  sodium  carbonate  and 
heating  on  charcoal  in  the  reducing  flame.  The  globules  of  the 
metal  thus  obtained  are  readily  fusible  and  are  bright  when  in  the 
flame,  but  become  covered  with  a  coating  of  oxide  when  exposed 


Bismuth  REACTIONS   OF   THE   ELEMENTS.  55 

to  the  air.  They  are  brittle,  and,  if  removed  from  the  charcoal 
and  hammered  on  an  anvil,  they  may  flatten  to  some  extent  at  first, 
but  cannot  be  beaten  into  a  thin  sheet  like  lead.  Heated  before 
the  blowpipe,  bismuth  is  somewhat  volatile,  and  its  vapor  passing 
into  the  air  becomes  oxidized,  and  settles  on  the  coal  as  a  lemon-  to 
orange-yellow  coating  of  bismuth  oxide,  which  is  white  at  a  dis- 
tance from  the  assay.  The  coating  may  be  volatilized  by  heating 
in  both  the  oxidizing  and  reducing  flames  without  imparting  any 
color  to  them.  The  reactions  are  quite  similar  to  those  of  lead, 
but  may  be  distinguished  by  the  iodine  tests. 

Make  the  test  by  heating  any  simple  bismuth  mineral,  or  the  commer- 
cial oxide  of  bismuth,  as  directed  above.  A  somewhat  better  idea  of  the 
bismuth  coating  may  be  obtained  by  removing  a  globule  of  the  metal  and 
heating  it  alone  before  the  blowpipe  on  a  fresh  piece  of  charcoal. 

2.  Iodine   Tests. — An  excellent  test  proposed  by  von  Kobell 
consists  in  adding  to  a  small  portion  of  the  powdered  mineral 
3  or  4  times  its  volume  of  a  mixture  of   potassium  iodide  and 
sulphur  (p.  26),    and  heating  before   the  blowpipe  on  charcoal 
with  a  small  oxidizing  flame,  when  a  coating  is  produced  which 
is  yellow  near  the  assay,  and  bordered  on  the  outer  edges  by  a 
brilliant  red. 

The  test  on  a  gypsum  plate,  made  as  directed  on  p.  17,  yields 
a  chocolate-brown  coating  of  bismuth  iodide,  which  is  changed  to 
a  brilliant  red  by  exposing  for  a  short  time  to  the  fumes  of  strong 
ammonia. 

3.  Tests  in  the  Wet  Way. — If  the  mineral  is  soluble  in  hydro- 
chloric acid,  evaporate  the  solution  until  only  a  few  drops  remain, 
and  then  pour  it  into  a  test-tube  about  one  third  full  of  water,  when 
a  white  precipitate  of  bismuth  oxychloride,  BiOCl,  will  form,  which 
may  be  collected  on  a  filter  and  tested,  as  in  §  1.     If  the  mineral  is 
not  soluble  in  hydrochloric  acid,  dissolve  in  nitric,  then  add  excess 
of  hydrochloric  acid,  concentrate  to  a  small  volume  and  pour  into 
water,  as  directed  above.     If  the  presence  of  lead  is  suspected, 
dissolve  in  nitric  and  2  or  3  cc.  of  concentrated  sulphuric  acid, 
evaporate  in  a  casserole  until  the  nitric  acid  is  all  expelled,  and> 


56  REACTIONS   OF   THE   ELEMENTS.  Boron 

after  cooling,  digest  with  water  and  filter  off  the  insoluble  lead 
sulphate,  which  may  be  tested  according  to  p.  87,  §  1.  To  the 
filtrate,  add  ammonia  to  precipitate  bismuth  hydroxide,  and  this, 
when  collected  on  a  filter,  may  be  tested  according  to  §  1. 

Boron,  B. — Trivalent.     Atomic  weight,  11. 

OCCURRENCE. — Boron  is  the  characteristic,  non-metallic  ele- 
ment of  boric  acid,  H3BO3,  and  its  salts,  the  borates.  The  latter 
are  not  very  common,  borax,  Na2B4O7.10H2O,  being  the  most  im- 
portant. Boron  is  also  found  as  a  constituent  of  a  number  of  sili- 
cates ;  as  tourmaline,  axinite,  datolite,  and  danburite.  Boron 
minerals  have  usually  been  formed  by  the  action  of  vapors  given 
off  during  igneous  activity. 

DETECTION. — Boron  may  be  detected  by  the  flame  coloration 
and  the  test  with  turmeric-paper. 

1.  Flame  Test. — Many  boron  minerals  when  heated  before  the 
blowpipe  impart  a  green  color  to  the  flame.     The  color  is  a  rather 
bright    one,   inclining    somewhat  to    yellow    (siskin-green),  anu 
must  not  be  confounded  with  that  of  barium,  from  which  it  may 
readily  be  distinguished  by  other  tests. 

Minerals  which  do  not  give  the  boron  flame  when  heated  alone 
usually  show  it  when  their  powder  is  mixed  intimately  with  about 
3  volumes  of  the  potassium  bisulphate  and  fluorite  mixture 
(p.  26),  and  heated  rather  gently  before  the  blowpipe  or  in  a  Bun- 
sen-burner  flame.  The  mixture  is  most  conveniently  introduced 
into  the  flame  by  taking  up  a  little  of  it  on  the  end  of  a  hot  plati- 
num wire  or  in  a  small  loop.  The  hydrofluoric  acid  liberated  by 
the  mixture  attacks  the  mineral,  forming  boron  fluoride,  BF9,  and 
this  gives  a  green  flame  coloration,  which  is  usually  of  only  mo- 
mentary duration. 

Tests  may  be  made  with  datolite,  Ca(BOH)Si04,  or  danburite, 
CaB2(Si04)2,  which  give  a  green  flame  color  when  heated  alone,  and  also 
with  tourmaline,  in  which  case  it  is  necessary  to  make  use  of  the  potassium 
bisulphate  and  fluorite  mixture. 

2.  Test  with  Turmeric-paper. — If  turmeric-paper  is  moistened 
with  a  dilute  hydrochloric  acid  solution  of  a  mineral  containing 


Cadmium  REACTIONS   OF   THE    ELEMENTS.  57 

boron,  and  then  dried  at  100°  C.  (on  the  outside  of  a  test-tube  con- 
taining boiling  water),  it  assumes  a  reddish-brown  color,  and  this 
is  changed  to  inky-black  by  moistening  with  ammonia.  The  test 
is  very  delicate  and  satisfactory,  and  may  be  applied  to  all  boron 
minerals,  for,  if  insoluble  in  acids,  they  may  be  dissolved  after 
fusion  with  sodium  carbonate,  as  directed  on  p.  110,  §§  3  and  4. 

Bromine,  Br. — Univalent.     Atomic  weight,  80. 

OCCURRENCE. — This  non-metallic  element  is  found  very  rarely  in  min- 
erals, the  only  ones  of  importance  being  the  silver  ores,  embolite,  AgCl  with 
AgBr,  and  bromyrite,  AgBr.  The  bromides,  salts  of  hydrobromic  acid, 
are  mostly  soluble  in  water. 

DETECTION. — Many  of  the  reactions  of  bromine  are  similar  to  those  of 
chlorine  and  iodine.  Silver  nitrate  precipitates  silver  bromide,  AgBr. 
"When  a  bromide  is  heated  in  a  bulb  tube  with  potassium  bisulphate  and 
pyrolusite,  bromine  is  liberated,  and  may  be  distinguished  by  the  red  color 
of  its  vapor,  and  the  formation  of  liquid  bromine  if  the  reaction  is  strong. 
(Chlorides  and  iodides  when  similarly  treated  yield  chlorine  gas  and  iodine, 
respectively.)  Silver  bromide,  when  heated  in  a  closed  tube  with  galena, 
yields  a  sublimate  of  lead  bromide,  which  is  sulphur-yellow  when  hot,  and 
white  when  cold. 

For  the  detection  of  bromine  in  presence  of  iodine,  see  p.  69. 

Cadmium,  Cd.— Bivalent.     Atomic  weight,  112. 

OCCURRENCE.— Cadmium  is  a  rather  rare  element,  and  is  mostly  found 
associated  with  zinc  in  some  varieties  of  sphalerite  and  smithsonite.  Only 
one  cadmium  mineral  is  known,  greenockite,  CdS. 

DETECTION. If  minerals  containing  cadmium  are  mixed  with  sodium 

carbonate  and  heated  before  the  blowpipe  on  a  flat  charcoal  surface  in  the 
reducing  flame,  metallic  cadmium  is  readily  formed  and  volatilized.  The 
element  unites  with  the  oxygen  of  the  air,  and  the  resulting  oxide  collects 
on  the  charcoal  as  a  reddish-brown  coating,  which  is  yellow  distant  from 
the  assay,  and  usually  iridescent  if  only  a  little  of  it  forms. 

In  the  presence  of  zinc,  the  foregoing  method  may  sometimes  be  em- 
ployed, since,  owing  to  the  ease  with  which  cadmium  is  reduced  and  vola- 
tilized, its  coating  will  appear  before  that  of  zinc.  It  is  better,  however,  to 
proceed  as  follows:  Dissolve  from  4  to  6  ivory  spoonfuls  of  the  mineral  in 
nitric  acid,  add  1  or  2  cc.  of  concentrated  sulphuric  acid,  and  evaporate  in 
a  casserole  until  the  nitric  acid  is  removed.  On  cooling,  add  about  100  cc. 
of  water  and  10  cc.  of  hydrochloric  acid,  filter,  and  pass  hydrogen  sulphide 
gas  through  the  filtrate  for  half  an  hour,  then  filter  off  the  precipitated 


58  REACTIONS   OF   THE    ELEMENTS.  Caesium 

cadmium  sulphide,  and  wash  with  water.  Place  the  paper  containing  the 
precipitate  upon  a  piece  of  charcoal,  add  sodium  carbonate,  and  heat  before 
the  blowpipe,  first  with  a  small  oxidizing  flame  until  the  paper  is  burned, 
and  then  in  a  reducing  flame  to  obtain  the  coating  of  cadmium  oxide. 

Caesium,  Cs.— Univalent.     Atomic  weight,  133. 

OCCURRENCE. — This  very  rare  alkali  metal  has  been  found  in  pollucite, 
H.,Cs4Al4(SiO,)9,  and  in  small  quantities  in  some  varieties  of  lepidolite  and 
beryl.  Rubidium  is  often  found  with  caesium. 

DETECTION. — Caesium  is  similar  to  potassium,  and  may  be  precipitated 
as  caesium  platinic  chloride,  CsaPtCl6  (see  p.  106,  §  3).  The  precipitate  i» 
much  more  insoluble  than  the  corresponding  potassium  compound,  sepa^ 
rates  in  a  finer  condition,  and  has  a  paler  color.  To  make  sure  of  its  iden- 
tity, it  is  best  to  heat  some  of  the  precipitate  on  a  platinum  wire,  and 
examine  the  flame  with  a  spectroscope. 

Calcium,  Ca. — Bivalent.     Atomic  weight,  40. 

OCCURRENCE. — This  alkali-earth  metal  is  found  very  abun- 
dantly in  nature  (see  p.  3).  It  is  a  constituent  of  many  silicates 
and  of  most  rocks,  while  its  combinations  with  hydrofluoric,  car- 
bonic, sulphuric,  phosphoric,  and  other  acids  are  very  common. 
Examples  of  important  calcium  minerals  are  calcite,  GaCO, ; 
fluorite,  CaF2 ;  gypsum,  CaSO4.2H,O ;  pyroxene,  CaMg(SiO,)a; 
and  apatite,  Ca4(CaF)(PO4)3. 

DETECTION. — Usually,  the  best  methods  to  apply  are  the  alka- 
line reaction  after  heating,  and  the  precipitation  as  calcium  sul- 
phate, carbonate,  or  oxalate. 

1.  Alkaline  Reaction.  —  Calcium  minerals  become  alkaline 
upon  ignition  before  the  blowpipe,  with  the  exception  of  the 
silicates,  phosphates,  borates,  and  the  salts  of  a  few  rare  acids. 
A  similar  reaction  is  obtained  with  other  minerals  containing 
alkalies  and  alkaline  earths. 

a.  Heat  a  fragment  of  calcite  before  the  blowpipe,  and  place  it  upon  a 
piece  of  moistened  turmeric-paper.     In  this  experiment,  the  heat  drives  out 
C02  from  the  calcite,  leaving  lime,  CaO,  which  dissolves  to  some  extent  in 
the  water  and  gives  the  alkaline  reaction. 

b.  Heat  a  fragment  of  fluorite,  and  place  it  upon  moistened  turmeric- 
paper.     In  this  experiment,  water  (one  of  the  products  of  combustion)  reacts 
to  some  extent  upon  the  fluorite,  as  follows-  CaF2  -j-  HaO  —  CaO  +  2HF. 


Calcium  REACTIONS   OF   THE   ELEMENTS.  59 

Fluorite,  if  heated   in  a  closed  tube,  would  not  decompose  nor  become 
alkaline. 

c.  Heat  a  fragment  of  gypsum  and  test  on  turmeric-paper.  In  this  ex- 
periment, the  intense  heat  of  the  blowpipe  flame  is  perhaps  sufficient  to 
drive  out  S03  from  CaS04,  although  the  water  resulting  from  combustion 
undoubtedly  assists  very  much  in  bringing  about  the  decomposition  (com- 
pare p.  81,  §  1,  where  only  neutral  water  is  given  off  by  heating  gypsum 
in  a  closed  tube). 

2.  Flame  Test. — A  few  calcium  compounds  when  heated  before 
the  blowpipe  volatilize  to  some  extent  and  give  a  yellowish-red 
coloration  to  the  flame.     The  color  is  often  weak,  and  in  testing 
most  calcium  minerals  it  does  not  appear  at  all.     Since  calcium 
chloride  is  volatile,  the  color  may  often  be  observed  when   the 
assay  is  heated,   after  moistening  with  hydrochloric  acid.     The 
flame  must  not  be  mistaken  for  the  much  redder  one  of  strontium 
(see  p.  116,  §  1). 

Heat  a  fragment  of  calcite  in  the  platinum  forceps,  and  observe  that  it 
gives  only  a  very  little  or  no  color  to  the  flame ;  then  touch  it  to  a  drop  of 
hydrochloric  acid  and  heat  again.  Better  still,  mix  powdered  calcite  with 
a  drop  of  hydrochloric  acid,  then  touch  the  end  of  a  clean  platinum  wire 
to  the  mixture,  and  introduce  it  into  a  Bunsen-burner  or  blowpipe  flame. 

3.  Precipitation  as  Calcium  Sulphate  (Gypsum). — As  gypsum, 
CaS04.2H2O,  is  rather  insoluble  in  water,  and  sparingly  so  in  di- 
lute hydrochloric  acid,   it  may  be  precipitated  from  a  solution 
containing  calcium  upon  the  addition  of  a  few  drops  of  dilute 
sulphuric  acid,  provided  the  solution  is  neither  too  dilute  nor  too 
strongly  acid.     If  the  test  is  carried  out  according  to  the  details 
given  below,  it  will  be  found  a  very  convenient  one  for  the  detec- 
tion of  calcium. 

Dissolve  2  ivory  spoonfuls  of  calcite  in  a  test-tube  in  3  cc.  of  hydro- 
chloric acid,  divide  the  solution  into  2  parts,  dilute  one  with  about  10  times 
its  volume  of  water,  and  then  add  a  few  drops  of  dilute  sulphuric  acid  to 
each.  The  precipitate  which  forms  in  the  concentrated  solution  is  calcium 
sulphate,  and  this  will  dissolve  readily  upon  addition  of  water  and  warming 
(difference  from  strontium  and  barium).  No  precipitate  forms  in  the  dilute 
solution,  owing  to  the  solubility  of  the  calcium  sulphate. 


60  REACTIONS   OF  THE    ELEMENTS.  Calcium 

4.  BeJiamor  toward  Ammonia. — Calcium  is  not  precipitated 
from  solutions  upon  addition  of  ammonia,  except  when  carbonic, 
phosphoric,  silicic,  boric,  or  other  acids  are  present  with  which 
calcium  forms  insoluble  compounds.      This  behavior  is  very  im- 
portant, for  often  other  elements  which  are  present  with  calcium 
in  a  solution  may  be  precipitated  by  means  of  ammonia,  separated 
by  filtration,  and  the  calcium  detected  in  the  filtrate  by  the  tests 
given  beyond. 

a.  Dissolve  an  ivory  spoonful  of  calcite  in  a  test-tube  in  3  cc.  of  dilute 
hydrochloric  acid,  boil  for  a  few  seconds  to  expel  G402,  dilute  with  about  10 
cc.  of  water,  and  add  an  excess  of  ammonia;  i.e.,  until  the  solution  smells  of 
ammonia,  or  shows  a  blue  color  with  litmus-paper.     If  the  calcite  should 
be  impure,  traces  of  foreign  substances  may  be  precipitated,  but  no  calcium 
will  be  thrown  down.     Save  the  solution  for  experiments  under  §§  5  and  6. 

b.  Dissolve  an  ivory  spoonful  of  apatite,  calcium  phosphate,  in  a  test' 
tube,  in  3  cc.  of  hydrochloric  acid,  dilute  with  water,  and  add  ammonia  in 
excess.     In  this  experiment,  the  precipitate  which  forms  is  calcium  phos- 
phate, and  this,  although  soluble  in  acids,  is  insoluble  in  neutral  or  alkaline 
solutions. 

5.  Precipitation  as  Calcium  Carbonate. — Ammonium  carbon- 
ate added  to  a  solution  made  strongly  alkaline  with   ammonia 
precipitates  calcium  carbonate,  CaCOs.     If  made  from  a  boiling 
solution,  the  precipitation  is  practically  complete,  and  the  calcium 
can  be  removed  by  filtering. 

6.  Precipitation  as    Calcium   Oxalate. — Ammonium   oxalate 
added  to  an  alkaline  or  even  slightly  acid  solution  precipitates 
calcium  oxalate,  CaC2O4.     The  test  is  very  delicate,  and  the  sep- 
aration complete,  but  the  precipitate  comes  down  in  a  very  finely 
divided  condition,  and  is  apt  to  run  through  a  filter-paper.     It 
may  almost  always,  however,  be  readily  filtered  if  the  precipita- 
tion is  made  in  a  hot  solution,  and  then  allowed  to  stand  for  an 
hour  before  filtering. 

The  following  method  may  sometimes  be  found  convenient  for  the  de- 
tection of  calcium  in  phosphates:  Dissolve  an  ivory  spoonful  of  the  pow- 
dered mineral  in  a  test-tube  in  3  cc.  of  hydrochloric  acid,  add  ammonia 
until  a  precipitate  forms,  and  then  hydrochloric  acid,  a  drop  at  a  time, 


Carbon  KEACTIONS   OF   THE   ELEMENTS.  61 

until  the  solution  becomes  clear.  Dilute  now  with  about  10  cc.  of  water, 
and  add  ammonium  oxalate,  when,  if  calcium  is  present,  it  will  be  precipi- 
tated from  the  slightly  acid  solution  as  oxalate.  The  above  may  be  tested 
with  apatite. 

7.  For  the  detection  of  calcium  in  silicates  and  complex 
bodies,  see  p.  110,  §  4. 

Carbon,  C. — Tetravalent.     Atomic  weight,  12. 

OCCURRENCE. — Diamond  and  graphite  are  crystallized  forms  of 
carbon,  and  anthracite  coal  is  also  nearly  pure  carbon.  Bitumi- 
nous coal,  asphalt,  paraffin,  mineral  oils,  and  many  natural 
gases  are  different  forms  of  hydrocarbons;  i.e.,  combinations  of 
carbon  and  hydrogen,  for  which  usually  no  definite  chemical 
formulae  can  be  given,  and  which  cannot,  therefore,  be  classed  as 
definite  mineral  species.  The  carbonates,  salts  of  carbonic  acid, 
H3C03,  form  a  very  important  class  of  minerals,  including  such 
common  ones  as  calcite  and  aragonite,  CaCO3 ;  dolomite,  CaMg(CO3)2; 
siderite,  FeCO3 ,  and  many  others. 

DETECTION. — The  burning  of  carbon  with  formation  of  carbon 
dioxide,  and  the  closed-tube  reactions  serve  for  the  detection  of 
the  different  forms  of  coal,  hydrocarbons,  and  organic  substances. 
For  carbonates,  effervescence  with  acids  is  usually  a  sufficient 
test. 

Carbon,  Anthracite  and  Bituminous  Coals,  Hydrocarbons,  and 

Organic  Matter. 

Closed-tube  Reactions. — Hydrocarbons,  bituminous  coals,  and 
organic  matter,  when  heated  in  a  closed  tube,  usually  suffer 
destructive  distillation.  Tar-like  substances,  oils,  water,  and  gas 
are  given  off,  and  condense  in  the  tube,  while  a  strong  empyreumatic 
odor  may  usually  be  observed.  The  residue,  if  any  is  left,  is  gen- 
erally nearly  pure  carbon.  Anthracite  coal  and  the  different  forms 
of  nearly  pure  carbon  suffer  no  change  when  heated  in  a  closed 
tube,  except  that  perhaps  a  little  water  is  driven  off. 

a.  To  show  the  effect  of  organic  matter,  heat  a  small  fragment  of 
wood  in  a  closed  tube. 


62  REACTIONS   OF   THE   ELEMENTS. 


Carbon 


I.  Partly  fill  a  bulb  tube  or  a  large  closed  tube  with  bituminous  coal, 

;draw  out  the  upper  end,  as  in  Fig.  44, 
then  apply  heat  to  the  bulb,  and  set  fire 
to  the  escaping  gas.  If  the  residue  left 

in  the  tube  forms  a  hard,  coherent,  vesi- 
FIG.  44.  T  .,  ,  ,    .     ,. 

cular   mass  it  would  indicate   a   coking 

coalt  while  if  soft  and  pulverulent,  it  would  indicate  a  non-coking  coal. 

c.  Partly  fill  a  bulb  tube  or  a  large  closed  tube  with  pyrolusite,  Mn02 , 
carefully  shove  a  piece  of  anthracite  coal  to  a  position  near  the  pyrolusite, 
a,  Fig.  45,  and  apply  heat,  first  to  the 
coal  until  it  becomes  red  hot,  then  to 
the  pyrolusite.  As  oxygen  is  driven  ^^^  a 
from  the  pyrolusite,  the  coal  will  burn, 

and  continue  to  glow  as  long  as  the  supply  of  oxygen  lasts  or  any  of  the 
coal  remains  (compare  p.  100,  §  1). 

Graphite  is  a  form  of  carbon  which  burns  with  great  difficulty,  and 
cannot  be  tested  as  above,  while  diamond  burns  quite  readily,  provided  that 
.part  of  the  glass  where  the  diamond  is  located  is  heated  intensely  so  as  to 
jstart  the  combustion. 

(Jarbonates. 

1.  Effervescence  with  Acids . — When  carbonates  are  dissolved 
in  acids,  carbon  dioxide  gas,  C0a ,  is  given  off  with  effervescence. 
The  carbonates  are  salts  of  a  weak  acid,  and  when  treated  with  a 
strong  acid  they  are  decomposed,  yielding  salts  of  the  stronger, 
and  setting  the  weaker  acid  free.  Theoretical  carbonic  acid  is 
H2CO8 ,  but  when  liberated  it  splits  up  into  H20  and  CO3.  There- 
fore, the  reaction  between  calcium  carbonate  and  hydrochloric 
acid  may  be  represented  as  follows :  CaCO3  +  2HC1  = 
CaCl2  +  H2O  +  CO3.  Any  strong  acid  (hydrochloric,  nitric,  or 
sulphuric)  may  be  used  to  liberate  carbon  dioxide,  by  strong  be- 
ing meant  one  with  strong  chemical  affinity,  not  a  concentrated 
acid.  The  reaction  usually  succeeds  best  when  dilute  hydro- 
chloric acid  is  used,  and  it  may  take  place  in  the  cold,  although 
sometimes  it  is  necessary  to  apply  heat.  When  heat  has  to  be 
applied,  care  must  be  taken  not  to  mistake  boiling  and  escaping 
bubbles  of  steam  for  carbon  dioxide.  Carbon  dioxide  is  charac- 
terized by  being  a  heavy,  colorless,  and  odorless  gas,  which  is  not 
aDt  to  be  confounded  with  other  gases.  It  does  not  support  com- 


Carbon  BEACTIONS   OF   THE   ELEMENTS.  63 

bustion,  and,  when  brought  in  contact  with  clear  barium  hydrox- 
ide solution,  it  gives  a  white  precipitate  of  barium  carbonate. 
CO,  +  BaO2H2  =  BaC03  +  H2O. 

a.  Take  2  ivory  spoonfuls  of  powdered  calcite  in  a  test-tube,  add  a 
little  water  and  an  equal  quantity  of  hydrochloric  acid,  when  an  efferves- 
cence will  be  observed,  and  the  air  will  soon  be  displaced  by  the  heavier 
carbon  dioxide,  if  the  tube  is  held  vertically.  A  burning  match,  if  thrust 
into  the  tube,  will  be  immediately  extinguished.  Pour  a  little  barium 
hydroxide  solution  into  a  second  test-tube,  and,  holding  the  two  tubes  mouth 
to  mouth,  incline  the  one  containing  the  carbon  dioxide,  so  that  the  heavy 
gas  can  pour  down  into  the  one  containing  the  barium  hydroxide,  when,  on 
shaking  the  latter,  a  white  precipitate  of  barium  carbonate  will  appear.  It 
is  evident  that  the  test  with  barium  hydroxide,  made  as  suggested  above, 
can  be  used  only  when  carbon  dioxide  is  abundantly  given  off  and  the  tube 
is  filled  with  the  gas. 

A  more  delicate  method  of  testing  with  barium  hydroxide  is  to  make 
use  of  a  tube  like  the  one  shown  in  Fig.  46.  Fragments  of  the  carbonate 


FIG.  46. 

to  be  tested  are  placed  in  the  lower  bulb,  and,  by  means  of  a  pipette,  dilute 
acid  is  introduced,  care  being  taken  not  to  allow  any  of  it  to  get  into  the 
upper  bulb,  or  on  the  sides  of  the  tube  above  the  latter.  The  tube  being 
held  nearly  horizontal,  barium  hydroxide  is  then  introduced  into  the  upper 
bulb,  where  a  precipitate  of  barium  carbonate  will  be  formed  by  the  escap- 
ing carbon  dioxide. 

Effervescence  may  be  detected  in  a  minute  particle  of  mineral  by  bring- 
ing the  latter  in  contact  with  a  drop  of  acid  on  a  watch-glass  or  in  a  test- 
tube. 

b.  Take  some  dolomite,  CaMg(C03)Q,  and  treat  it  exactly  as  described 
under  a,  and  it  will  be  observed  that  only  a  very  slight  or  no  effervescence 
takes  place  in  the  cold,  but,  on  warming,  carbon  dioxide  is  abundantly  given 
off.     In  testing  carbonates  which  are  soluble  only  in  hot  acids,  it  is  best  to 
have  the   mineral  finely   pulverized.     Care  must  always  be   taken  not  to 
mistake  boiling  for  effervescence. 

c.  The  mistake  is  sometimes  made  of  testing  carbonates  with  acids  which 
are  too  concentrated,  as  illustrated  by  the  following  experiments:  In  dry 


64  REACTIONS   OF   THE   ELEMENTS.  Carbon 

test-tubes  treat  fragments  of  witherite,  BaC03,  with  concentrated  hydro- 
chloric acid,  and  cerussite,  PbC03,  with  concentrated  nitric  acid,  and,  in 
both  cases,  there  will  be  only  a  very  trifling  or  no  effervescence,  owing  to 
the  insolubility  of  barium  chloride  and  lead  nitrate  in  the  respective  acids. 
On  dilution  with  2  or  3  volumes  of  water,  however,  effervescence  will 
commence,  because  the  salts  which  form  on  the  outside  of  the  fragments 
dissolve,  and  thus  fresh  surfaces  of  the  carbonates  are  constantly  exposed  to 
the  action  of  the  acids. 

d.  In  order  to  show  that  there  is  sometimes  danger  of  overlooking  a 
small  quantity  of  a  carbonate,  test  as  follows :  Dissolve  from  ^  to  i  of  an 
ivory  spoonful  of  sodium  carbonate  in  5  cc.  of  cold  water,  and  add  a  little 
hydrochloric  acid,  when  no  or  only  a  slight  effervescence  will  be  visible, 
owing  to  the  fact  that  carbon  dioxide  is  soluble  to  some  extent,  and  remains 
dissolved  in  the  liquid.  On  heating,  the  gas  makes  its  appearance. 

2.  Decomposition  by  Heating:  Closed-tube  Reaction.—  Car 
bonates  when  heated  are  usually  decomposed,  carbon  dioxide 
going  off  and  oxides  of  the  metals  being  left.  An  exceedingly 
delicate  test  may  be  made  by  heating  a  small  particle  of  a  carbon- 
ate in  a  closed  tube,  and  testing  for  the  presence  of  carbon 
dioxide,  by  bringing  a  little  barium  hydroxide  solution  into  the 
upper  end  of  the  tube  by  means  of  a  capillary  pipette. 

The  ease  with  which  carbonates  decompose  depends  upon  the 
character  of  the  metals  with  which  the  carbonic  acid  radical  is  in 
combination.  Carbonates  of  the  metals  with  strong  chemical 
affinity,  such  as  potassium  or  sodium,  are  not  decomposed  at  a  red 
heat,  while  those  with  weak  chemical  affinity,  like  iron  or  zinc, 
decompose  at  a  moderate  temperature.  Calcium  occupies  an  inter- 
mediate position,  and  calcite,  or  limestone,  CaCOs ,  is  not  decom- 
posed at  a  low  red  heat,  but  is  wholly  converted  by  intense 
ignition  into  CaO,  as  illustrated  by  the  familiar  example  of  burn- 
ing lime.  CaCO3  =  CaO  +  CO2. 

Make  the  experiment  by  heating  a  small  fragment  of  siderite,  FeC03,  in 
a  closed  tube,  and  observe  that  the  brown,  non-magnetic  mineral  is  changed 
to  black  magnetic  oxide  of  iron,  while  the  carbon  dioxide  in  the  tube  may 
be  detected  by  means  of  barium  hydroxide. 

Cerium,  Ce. — Usually  trivalent,  but  tetravalent  in  eerie  com- 
pounds. Atomic  weight,  140. 


REACTIONS   OF   THE   ELEMENTS.  65 

In  connection  with  cerium  it  will  be  well  to  consider  a  number  of  other 
elements,  known  as  the  Rare  Earth  Metals.  The  more  important  of  these 
are  lanthanum,  La;  didymium,  Di;  yttrium,  Y;  erbium,  Er;  and  thorium, 
Th.  This  group,  however,  has  been  further  subdivided,  so  that  it  now 
includes  gadolinium,  neodymium,  praseodymium,  samarium,  scandium,  ter- 
bium, thulium,  and  ytterbium,  but  the  reactions  for  these  rare  substances 
are  so  obscure  and  difficult  that  no  attempt  will  be  made  to  give  them  in 
the  present  work. 

OCCURRENCE. — The  rare  earths  are  usually  found  associated  with  one 
another,  and  minerals  containing  essentially  the  cerium  group  (Ce,  La,  and 
Di)  are  cerite,  allanite,  monazite,  fergusonite,  samarskite,  tysonite,  parisite, 
and  bastnaesite.  The  yttrium  earths  (Y  and  Er)  are  found  especially  in 
gadolinite,  xenotime,  yttrotantalite,  euxenite,  polycrase,  and  sipylite.  Tho- 
rium is  found  in  thorite,  monazite,  aeschynite,  polymignite,  and  thoro- 
gummite. 

DETECTION. — The  rare  earths  are  all  precipitated  as  hydroxides  from 
acid  solutions  by  means  of  ammonium  or  potassium  hydroxides,  but  this 
precipitation  may  be  often  omitted  when  it  is  known  that  calcium  is 
absent.  The  precipitate  when  filtered  and  washed  is  dissolved  in  hydro- 
chloric acid,  the  excess  of  acid  removed  by  evaporation,  the  residue 
dissolved  in  water,  and  oxalic  acid  added,  when  a  precipitate  of  oxalates 
of  the  earths  will  be  thrown  down,  which  is  insoluble  in  oxalic  acid. 
The  precipitate  when  filtered,  washed,  and  ignited,  yields  oxides  of  the 
earths. 

In  order  to  detect  thorium,  the  oxides  are  dissolved  by  boiling  with  a  few 
cc.  of  dilute  sulphuric  acid,  the  solution  evaporated,  transferred  finally  to  a 
crucible,  and  heated  carefully  until  the  excess  of  sulphuric  acid  is  wholly 
driven  off,  thus  converting  the  earths  into  normal  sulphates.  The  sulphuric 
acid  must  be  driven  off  in  a  good  draft,  for  the  fumes  are  very  irritating, 
and  in  order  to  regulate  the  heat  it  is  best  to  place  the  crucible  containing 
the  sulphates  inside  a  porcelain  one,  thus  leaving  an  air  space  between,  and 
to  adjust  the  heat  so  that  the  outer  crucible  is  not  heated  above  faint  red- 
ness. The  crucible  should  be  covered  toward  the  end  of  the  operation,  and 
the  heating  continued  until  no  white  fumes  appear  when  the  cover  is 
raised.  If  the  sulphates  have  been  properly  heated,  they  should  be  wholly 
soluble  in  cold  water,  and  thorium  may  then  be  precipitated  from  the  dilute 
solution  by  adding  sodium  thiosulphate,  Na2S,03,  and  boiling.  The  pre- 
cipitate, when  collected  on  a  filter-paper,  washed,  and  ignited,  yields  tho- 
rium oxide,  Th02.  Zirconium,  if  present,  will  precipitate  with  thorium, 
and,  from  solutions  which  are  too  concentrated,  cerium  may  also  be  precipi- 
tated. To  make  certain,  therefore,  of  the  identity  of  the  thorium,  it  will 
be  best  to  convert  the  ignited  material  again  into  sulphate,  and  to  repeat 
the  precipitation  with  sodium  thiosulphate. 


66  EEACTIONS   OF  THE   ELEMENTS.  Cerium 

In  order  to  detect  the  remaining  groups,  the  earths  contained  in  the 
filtrate  from  the  thorium  are  precipitated  by  means  of  oxalic  acid,  and 
converted  into  sulphates,  as  directed  above.  The  sulphates  are  then 
dissolved  in  a  little  cold  water,  and  about  2  volumes  of  a  boiling,  saturated 
solution  of  potassium  sulphate  are  added,  which  precipitates  Ce,  La, 
and  Di  completely,  as  double  potassium  sulphates,  Ce2(S04)s  -f  3K2S04, 
while  Y  and  Er  remain  in  solution.  After  standing  a  few  hours  in  the 
cold,  the  precipitate  may  be  filtered,  and  washed  with  a  cold  saturated 
solution  of  potassium  sulphate.  From  the  filtrate,  Y  and  Er  may  be 
then  precipitated  by  means  of  ammonium  oxalate,  while  the  precipitate 
containing  Ce,  La,  and  Di,  may  be  dissolved  in  hot  hydrochloric  acid, 
and  the  earths  precipitated  by  addition  of  ammonium  oxalate  and  am- 
monia. The  detection  of  the  separate  elements  in  the  two  groups  is  a 
difficult  matter,  arid  is  usually  not  very  important.  Ce,  La,  and  Di  almost 
invariably  occur  together,  while  Y  and  Er  are  usually  associated  with  one 
another. 

In  the  cerium  group,  pure  ignited  oxide  of  cerium,  Ce02,  is  nearly 
white,  as  are  also  the  oxides  of  lanthanum,  La203,  and  didymium,  Di203, 
but  a  mixture  of  cerium  oxide  with  the  latter  always  has  a  brown 
color.  If  the  solution  of  the  ignited  oxides  in  sulphuric  acid  is  yellow, 
it  indicates  cerium,  and  is  due  to  eerie  sulphate,  Ce(S04)a.  After  ignit- 
ing the  sulphates,  however,  cerous  sulphate,  Ce2(S04)3,  is  formed,  which 
gives  a  colorless  solution.  If  the  oxides  are  dissolved  in  a  borax  bead 
in  the  oxidizing  flame  a  brownish-red  or  yellow  bead,  fading  to  yellow 
on  cooling,  indicates  cerium.  In  the  reducing  flame,  the  bead  becomes 
colorless  or  nearly  so.  With  phosphorus  salt,  the  colors  for  cerium  in  the 
oxidizing  flame  are  yellow  when  hot,  fading  to  colorless  when  cold,  and 
in  the  reducing  flame,  colorless  both  when  hot  and  cold.  When  cerium 
does  not  interfere,  didymium  may  be  detected  by  means  of  the  borax 
or  salt  of  phosphorus  beads,  for  when  a  considerable  quantity  is  dis- 
solved it  imparts  to  them  a  pale  rose  color  in  both  the  oxidizing  and 
reducing  flames.  Didymium  also  imparts  to  solutions  a  pale  rose  color, 
which  may  be  seen  when  they  are  concentrated.  If  a  solution  is  held 
before  the  slit  of  a  spectroscope  directed  toward  a  strong  light,  or  if  the 
oxalate  precipitate  is  held  in  a  strong  light  and  examined  with  a  spectro- 
scope, dark  bands  may  be  seen  interrupting  the  continuous  spectrum, 
which  are  known  as  absorption  bands,  and  indicate  the  presence  of  the 
didymium  group  among  the  elements  precipitated  by  potassium  sulphate. 
A  prominent  band  is  located  in  the  yellow,  and  another  about  the  middle 
of  the  green. 

Yttrium  gives  no  absorption  spectrum,  but  erbium  and  the  rare  earths 
related  to  it  give  a  series  of  strong  absorption  bands. 


Chlorine  EEACTIONS   OF   THE   ELEMENTS.  67 

Chlorine,  Cl. — Univalent.     Atomic  weight,  35.5. 

OCCURRENCE. — Chlorine  is  the  characteristic  non-metallic  ele- 
ment of  hydrochloric  acid,  HC1,  and  the  chlorides.  With  the 
exception  of  silver,  lead,  and  mercurous  chlorides,  the  simple 
chlorides  of  the  metals  are  soluble  in  water,  and  their  occurrence, 
therefore,  as  minerals  is  rather  restricted,  since  they  cannot  occur 
where  water  is  abundant.  Of  the  soluble  chlorides,  halite,  JS"aCl ; 
sylvite,  KC1;  and  carnalite,  KMgCl3.6H2O;  and  of  the  insoluble 
ones,  cerargyrite,  AgCl,  are  the  most  important  minerals.  A 
number  of  combinations  of  chlorides  with  oxides  or  hydroxides 
of  the  metals,  called  oxy chlorides,  are  known,  and  chlorine  is  fre- 
quently found  in  combination  with  other  acids,  especially  silicic 
and  phosphoric,  and  is  then  often  isomorphous  with  fluorine 
and  hydroxyl.  Examples  are  atacamite,  Cu2Cl(OH)3  or  CuCl, 
+  3Cu(OH)2 ;  sodalite,  Na4(AlCl)Al2(SiO4)3 ;  and  pyromorphite, 
Pb4(PbCl)(P04)3. 

DETECTION. — The  most  satisfactory  tests  for  chlorine  are  pre- 
cipitation as  silver  chloride,  or  the  formation  of  chlorine  gas. 

1.  Precipitation  as  Silver  Chloride. — Silver  chloride,  AgCl,  is 
very  insoluble  in  water  and  dilute  nitric  acid.  A  very  delicate 
test  may  therefore  be  made  by  dissolving  a  chloride  in  water  or 
dilute  nitric  acid,  and  precipitating  silver  chloride  by  adding  a 
few  drops  of  a  solution  of  silver  nitrate.  Bromine  and  iodine 
give  similar  reactions.  If  much  chlorine  is  present,  a  white, 
curdy  precipitate  forms,  or,  if  a  trace  is  present,  there  is  at  first 
only  a  bluish- white  opalescence.  On  exposure  to  light,  the  pre- 
cipitate soon  acquires  a  violet  color. 

In  order  to  apply  this  test  to  minerals  which  are  insoluble  in 
acids,  first  fuse  with  sodium  carbonate,  as  directed  under  silicates 
(p.  110,  §  4),  soak  out  the  fusion  with  water  and  dilute  nitric  acid, 
filter  if  necessary,  and  then  add  silver  nitrate. 

To  illustrate  this  test,  dissolve  J  ivory  spoonful  of  halite  (common  salt) 
in  a  few  cc.  of  water,  and  then  add  a  few  drops  of  nitric  acid  and  of  silver 
nitrate.  NaCl  +  AgN03  =  AgCl  -j-  NaN03.  Test  the  solubility  of  the 
precipitate  in  an  excess  of  ammonia. 


68  REACTIONS   OF   THE   ELEMENTS.  Chlorine 

2.  Evolution  of  Chlorine. — A  very  satisfactory  test  in  the  dry 
way  may  be  made  by  mixing  the  powdered  chloride  with  about 
4  times  its  volume   of  potassium   bisulphate  and  a  little  pow- 
dered pyrolusite,  MnO2 ,  and  heating  the  mixture  either  in  a  bulb 
tube  or  a  small  test-tube,  when  chlorine  gas  will  be  given  off,  and 
may  be  recognized  by  its  pungent  odor  or  its  bleaching  action  on 
a  strip  of  moistened  litmus-paper  held  inside  the  tube  (compare 
p.  101,  §2). 

Insoluble  compounds,  such  as  silver  chloride  or  a  silicate, 
should  first  be  fused  with  sodium  carbonate,  the  fusion  pul- 
verized, and  then  treated  as  above. 

3.  Flame  Test. — Chloride  of  copper  is  volatile  before  the  blow- 
pipe, giving  an  azure-blue  and  sometimes  a  green  coloration  to 
the  flame  (compare  Copper,  p.  72,    §  1).     To  use  this  behavior  for 
the  detection  of  chlorine,  Berzelius  recommended  the  following 
treatment :  To  a  small  salt  of  phosphorus  bead  add  copper  oxide 
until  the  bead  is  dark  and  opaque,  then  touch  it  while  hot  to  the 
substance  to  be  tested,  and  heat  before  the  blowpipe  in  an  oxidiz- 
ing flame,  when  chloride  of  copper  will  volatilize  and  impart  a 
blue  color  to  the  flame.     The  test  answers  very  well  for  most 
chlorides,  but  is  not  sufficiently  delicate  for  the  detection  of  small 
quantities  of  chlorine  in  minerals.     Bromine  gives  a  similar  reac- 
tion. 

4.  To  distinguish  silver  chloride,  silver  bromide,  and  silver 
iodide  from  one  another,  the  following  method  will  be  found  very 
convenient :  Heat  a  fragment  of  the  mineral  and  a  little  pure,  pul- 
verized galena  together  in  a  closed  tube,  and  observe  the  color  of 
the  sublimate  formed.     Silver  chloride  yields  lead  chloride,  and 
this  fuses  on  the  hot  glass  to  colorless  globules  which  become 
white  when  cold.     Silver  bromide  yields  lead  bromide,  which  is 
sulphur-yellow  when  hot  and  white  when  cold.     Silver  iodide 
yields  lead  iodide,  which  is  dark  orange-red  when  hot  and  lemon- 
yellow  when  cold.     If  iodine  is  detected  by  the  foregoing  test, 
bromine  and  chlorine  may  also  be  present,  and,  if  iodine  is  absent, 
the  reaction  for  bromine  will  obscure  that  of  chlorine. 


Chromium  REACTIONS  OF  THE   ELEMENTS.  69 

5.  The  detection  of  chlorine  in  the  presence  of  bromine  and  iodine  is 
not  a  simple  matter.  If  combined  with  silver,  place  the  material  in  a  test- 
tube  with  some  granulated  zinc,  add  dilute  sulphuric  acid,  allow  the  reduc- 
tion to  proceed  for  some  minutes,  and  then  filter  or  decant  the  solution  of 
zinc  salts  from  the  insoluble  silver.  Take  a  few  drops  of  the  solution  in  a 
test-tube,  add  some  starch  paste  (a  little  starch  boiled  up  with  considerable 
water),  and  then  a  little,  red,  fuming  nitric  acid,  when,  if  iodine  is  present, 
it  will  impart  a  deep  blue  color  to  the  starch.  To  the  blue  solution  add 
chlorine  water  drop  by  drop,  which  at  first  sets  iodine  free,  but,  when  added 
in  excess,  combines  with  it  to  form  a  colorless  compound.  Continue,  there- 
fore, to  add  the  chlorine  water  until  the  color  of  iodine  disappears,  when,  if 
bromine  is  absent,  the  solution  will  be  colorless,  but,  if  present,  it  will  be 
yellowish-red,  owing  to  liberated  bromine.  This  color  shows  more  dis- 
tinctly when  the  liquid  is  agitated  with  carbon  disulphide,  which  dissolves 
the  bromine. 

For  the  detection  of  chlorine,  provided  bromine  and  iodine  are  present, 
take  another  portion  of  the  solution,  add  silver  nitrate  and  a  little  nitric 
acid,  and  then  filter  off  and  wash  the  precipitate,  which  may  contain  AgCl, 
AgBr,  and  Agl.  Transfer  this  to  a  beaker,  treat  with  ammonia  to  dissolve 
AgCl  and  AgBr,  filter  from  the  insoluble  Agl,  then  precipitate  the  silver 
salts  from  the  filtrate  by  addition  of  nitric  acid,  and  collect  them  on  a 
filter.  Mix  the  moist  precipitate  on  charcoal  with  a  little  more  than  its 
volume  of  sodium  carbonate,  fuse  before  the  blowpipe,  cut  away  the  fusion, 
treat  it  with  hot  water,  filter  the  soluble  sodium  chlo- 
ride and  bromide  from  the  silver,  and  evaporate  the 
filtrate  to  dryness  in  a  dish  or  casserole.  Grind  the 
dried  residue  with  an  equal  volume  of  potassium  di- 
chromate,  transfer  to  a  tubulated  test-tube,  Fig.  47, 
add  a  little  concentrated  sulphuric  acid,  close  with  a 
stopper,  and  warm,  when,  if  chlorine  is  present,  it 
forms  with  the  chromium  a  red  gas,  CrCl202 ,  which 
condenses  to  a  liquid  of  the  same  color,  while  bromine 
forms  red  vapors  of  bromine.  If  some  of  the  red 
vapors  are  distilled  over  into  a  second  test-tube,  and 
are  then  treated  with  a  little  ammonia,  the  bromine  will  be  converted 
wholly  into  colorless  compounds,  while  the  OC1202  will  yield  ammonium 
chromate,  which  is  yellow.  The  yellow  color  of  ammonium  chromate  in 
the  second  test-tube  is,  therefore,  a  proof  that  chlorine  was  present. 

Chromium,  Cr. — Trivalent  and  sexivalent.    Atomic  weight,  52.5, 

OCCURRENCE. — Chromium  is  not  a  very  abundant  element,  and 
the  mineral  from  which  nearly  all  its  commercial  compounds  are 


70  REACTIONS   OF   THE   ELEMENTS.  Chromium 

made  is  chromite,  FeCrO4  —  FeO.Cr,O3.  The  element  is  found,  in 
small  quantities,  in  some  varieties  of  spinel,  garnet,  muscovite, 
beryl,  clinochlore,  and  other  minerals  where  O2O3  is  isomorphous 
with  A12O3  or  Fe2O3.  Of  the  chromates,  crocoite,  PbCrO4,  is  the 
commonest. 

DETECTION. — The  colors  which  chromium  imparts  to  the  fluxes 
usually  serve  for  its  detection. 

1.  Test  with  a  Borax  Bead. — If  a  very  little  oxide  of  chromium 
is  dissolved  before  the  blowpipe  in  a  borax  bead  in  the  oxidizing 
flame,  the  bead  will  be  decided  yellow  when  hot,  changing  to  yel- 
lowish-green when  cold.  With  more  of  the  oxide,  the  colors  are 
deeper,  red  when  hot,  changing  through  yellow  to  a  fine  yellowish- 
green  when  cold.  After  heating  in  the  reducing  flame,  as  soon  as 
the  bead  cools  below  a  red  heat,  it  assumes  a  fine  green  color,  and 
shows  none  of  the  yellow  which  is  so  prominent  after  heating  in 
the  oxidizing  flame.  It  is  probable  that  the  color  produced  in  the 
oxidizing  flame  depends  upon  the  presence  of  CrO3 ,  the  anhydride 
of  chromic  acid,  salts  of  which  are  yellow  or  red ;  while  in  the 
reducing  flame  the  basic  oxide  Cr2O3  is  formed,  which  usually 
imparts  an  intense  green  color  to  solutions. 

N0.  Test  with  Salt  of  Phosphorus. — The  colors  which  are  ob- 
tained in  the  oxidizing  flame  with  this  flux  are  dirty  green  when  hot, 
changing  to  fine  green  when  cold.  After  reduction,  the  colors  are 
about  the  same  as  in  the  oxidizing  flame,  but  not  so  decided. 

Chromium  must  not  be  confounded  with  vanadium,  which  gives 
in  the  reducing  flame  almost  identical  reactions  with  the  fluxes, 
but  in  the  oxidizing  flame  differs  in  yielding  a  yellow  bead  with 
salt  of  phosphorus,  which  flux  never  acquires  other  than  a  green 
color  with  chromium. 

3.  Special  Tests  for  Small  Quantities  of  CJiromium  when  Associated 
with  other  Substances  which  Color  the  Fluxes.— -If  the  mineral  is  a  silicate, 
fuse  it  in  a  platinum  spoon  with  about  4  volumes  of  sodium  carbonate  and 
2  of  potassium  nitrate,  by  which  means  an  alkali  chromate,  soluble  in 
water,  will  be  formed.  Soak  out  the  fusion  in  a  test-tube  with  about  5  cc. 
of  water,  filter,  and,  if  chromium  is  present,  the  filtrate  will  have  a  yellow 
color.  Make  the  filtrate  slightly  acid  with  acetic  acid,  filter  again  if  neces- 


Copper  REACTIONS   OF   THE   ELEMENTS.  71 

sary,  and  add  a  little  lead  acetate,  when  a  yellow  precipitate  of  lead  chro- 
mate  will  form,  which  may  be  collected  on  a  filter,  washed  with  water,  and 
tested  with  the  fluxes  (compare  Vanadium,  p.  130,  §  2).  If  the  precipitate 
is  very  small,  it  will  be  best  to  burn  the  paper  in  a  porcelain  crucible  and 
test  the  residue. 

If  the  mineral  is  an  oxide  difficult  to  decompose,  as  some  kinds  of  spinel 
or  chromite,  dissolve  as  much  as  possible  of  the  very  finely  powdered  mineral 
before  the  blowpipe  in  a  borax  bead,  remove  the  latter  from  the  wire,  crush 
it  in  a  diamond  mortar,  then  mix  with  2  or  3  volumes  of  sodium  carbonate 
and  1  of  potassium  nitrate,  fuse  in  a  platinum  spoon,  and  proceed  exactly  as 
described  in  the  previous  paragraph. 

Cobalt,  Co. — Bivalent.     Atomic  weight,  59. 

OCCURRENCE. — Cobalt  is  a  comparatively  rare  element,  found 
usually  in  combination  with  sulphur  or  arsenic,  and  generally 
associated  with  nickel  and  iron,  with  which  it  is  isomorphous.  A 
few  of  its  more  important  compounds  are  linnaeite,  Co3S4 ;  smaltite, 
Co  As, ;  cobaltite,  CoSAs;  and  erythrite,  Co3(AsO4)2.8H2O. 

DETECTION. — The  blue  color  which  cobalt  oxide  imparts  to  the 
fluxes  serves  as  a  very  simple  and  delicate  means  for  its  detection. 

1.  Test  with  the  Fluxes. — Oxide  of  cobalt  is  soluble  before  the 
blowpipe  both  in  the  borax  and  salt  of  phosphorus  beads, 
imparting  to  them  a  fine  blue  color,  which  remains  the  same  in  both 
the  oxidizing  and  reducing  flames.  The  test  is  so  delicate  that 
cobalt  can  be  detected  in  the  presence  of  a  considerable  quantity 
of  iron  and  nickel. 

When  copper  or  nickel  interferes  with  the  test  for  cobalt, 
remove  the  bead  from  the  wire,  and  fuse  it  on  charcoal  with  a 
granule  of  tin  in  a  strong  reducing  flame,  until  the  copper  and 
nickel  are  reduced  to  the  metallic  state,  when  the  flux  will  show 
the  blue  color  of  cobalt. 

See  also  the  special  method  for  treating  minerals  containing 
cobalt,  nickel,  iron,  and  copper  (p.  97,  §  4). 

Columbium,  Cb. — See  Niobium. 

Copper,  Cu. — Bivalent  in  cupric  and  univalent  in  cuprous  com- 
pounds. Atomic  weight,  63.4. 

OCCURRENCE. — Copper  is  widely  distributed  in  nature  and  is 


72  KEACTKWS   Of   THE   ELEMENTS.  Copper 

found  in  a  great  many  minerals.  A  few  of  its  most  important 
compounds  are  chalcopyrite,  CuFeS2 ;  chalcocite,  CuaS ;  bornite, 
CusFeS8;  tetrahedrite,  essentially  Cu8Sb2S7 ;  malachite,  (CuOH)2CO,; 
and  cuprite,  CuaO.  Copper  also  occurs  in  the  native  state  abun- 
dantly in  a  few  localities. 

DETECTION.— The  flame  coloration,  the  formation  of  globules 
of  metallic  copper,  and  the  colors  imparted  to  fluxes  and  to  solu- 
tions make  the  detection  of  copper  a  very  easy  matter. 

1.  Flame  Tests. — If  finely  divided  oxide  of  copper  is  intro- 
duced into  a  colorless  flame,  it  imparts  to  it  an  emerald-green  color, 
which  may  sometimes  be  observed  on  heating  minerals  before  the 
blowpipe,  but  often  no  color  is  obtained  because  no  volatile  com- 
pound of  copper  is  present.  If  the  assay  is  moistened  with  hydro- 
chloric acid,  however,  copper  chloride,  which  is  volatile,  will  be 
formed,  and  this  gives  a  strong  azure-blue  color  to  the  flame,  tinged 
usually  on  the  outer  edges  with  emerald-green,  due  to  the  decom- 
position of  the  chloride  and  formation  of  copper  oxide.  The  flame 
test  for  copper  after  moistening  with  hydrochloric  acid  is  very 
delicate,  but  if  the  mineral  is  a  sulphide,  it  should  be  fused  in  the 
oxidizing  flame  or  roasted  before  applying  the  acid. 

a.  Take  a  piece  of  chalcopyrite  in  the  platinum  forceps,  heat  it  before 
the  blowpipe  in  the  oxidizing  flame,  then  touch  it  to  a  drop  of  hydrochloric 
acid,  and  heat  again.     The  copper  chloride  soon  volatilizes,  but  the  flame 
may  be  repeatedly  obtained  by  renewed  applications  of  acid. 

The  test  may  also  be  made  on  platinum  wire,  according  to  directions 
given  on  p.  35. 

b.  Roast  a  little  powdered  chalcopyrite  on  charcoal,  as  directed  on  p.  39. 
then  moisten  the  product  with  a  drop  of  hydrochloric  acid,  and  heat  before 
the  blowpipe  in  the  reducing  flame.     In  this  experiment,  the  azure-blue 
flame  of  copper  chloride  is  obtained  in  great  perfection,  and  the  surface  of 
the  charcoal  near  the  assay  will  show  the  copper  reaction  if  touched  with 
the  reducing  flame.     A  beautiful  emerald-green  flame  is  obtained  if  the 
assay  is  moistened  with  hydriodic  instead  of  hydrochloric  acid,  and  heated 
before  the  blowpipe. 

c.  In  order  to  show  the  green  flame   color   given  by  oxide  of  copper, 
take  a  little  malachite  or  cuprite  in  a  diamond  mortar,  and  pulverize  it  by 
striking  with  a  hammer  in  close  proximity  to  a  Bunsen-burner  flame,  so  that 
the  fine  dust  from  the  mortar  will  pass  into  the  flame. 


Copper  REACTIONS   OF   THE    ELEMENTS.  73 

2.  Reduction  on  Charcoal  to  Metallic  Copper. — From  copper 
oxides  and  minerals  containing  oxide  of  copper,  the  metal  may 
be  readily  reduced  and  obtained  as  fused  globules   by  heating 
intensely  in  a  reducing  flame,  with  a  flux,  on  charcoal.     Copper 
globules  are  bright  when   covered  with   the  reducing  flame,  but 
acquire  a  coating  of  black  oxide  on  exposure  to  the  air.     They  are 
malleable,  can  be  flattened  by  hammering  on  an  anvil,  and  show  the 
red  color  characteristic  of  copper.     The  best  flux  to  use  is  a  mix- 
ture of  equal  parts  of  sodium  carbonate  and  borax  :  This  serves  to 
keep  iron  and  other  difficultly  reducible  metals  in  solution,  as  in  a 
slag,  while  copper  may  easily  be  reduced  and  fused  to  a  globule. 
Minerals  containing  sulphur,  arsenic,  or  antimony  should  first  be 
carefully  roasted,   according  to  directions  given  on  p.  39,  then 
mixed  with  the  appropriate  flux,  and  reduced.    It  is  evident  that, 
when  other  readily  reducible  metals  are  present,  a  globule  will  be 
obtained  which  is  not  pure  copper. 

As  beginners  usually  have  some  difficulty  in  fusing  copper 
before  the  blowpipe  on  charcoal,  it  is  best  to  use  only  a  small  quan- 
tity of  the  mineral  and  flux.  About  i  to  i  ivory  spoonful  of  the 
mineral  and  two  or  three  times  as  much  flux  will  be  found  to  be  a 
suitable  quantity. 

Obtain  globules  of  copper  from  malachite,  using  a  mixture  of  sodium 
carbonate  and  borax  as  a  flux,  and  from  chalcopyrite,  which  must  first  be 
roasted  and  afterwards  fluxed  with  a  mixture  of  sodium  carbonate  and  borax, 

3.  Reactions  with  the  Fluxes. — Copper  oxide  dissolves  readily 
both  in  the  borax  and  salt  of  phosphorus  beads  on  platinum  wire. 
In  the  oxidizing  flame,  the  colors  are  green  when  hot,  but  change  to 
blue  when  cold.     The  color  is  due  to  the  presence  of  cupric  oxide, 
CuO,  and  the  test  is  very  delicate.     In  the  reducing  flame,  the 
colors  are  paler,  almost  colorless,  with  little  copper  ;  while  if  much 
is  present,  there  is  a  separation  of  cuprous  oxide,  Cu2O,  when  the 
fluxes  solidify,  which  renders  the  beads  opaque  and  red  by  reflected 
light.     A  still  better  way  to  show  this  reduction  is  to  remove  the 
bead  from  the  wire,  and,  placing  it  on  charcoal  with  a  small  grain 
of  tin,  to  fuse  the  two  together  in  a  reducing  flame.     The  bead 


74  KEACTIONS   OF   THE   ELEMENTS.  Copper 

will  then  be  clear  and  nearly  colorless  when  hot,  but  opaque  and 
red  on  solidifying.  The  action  of  the  tin  is  to  take  oxygen  from 
the  cupric  oxide,  changing  it  to  cuprous  oxide.  The  reaction  suc- 
ceeds best  with  the  salt  of  phosphorus  bead,  and  the  heating  on 
charcoal  in  either  case  must  not  be  too  hot  nor  continued  too  long  a 
time,  as  the  copper  may  thus  be  reduced  to  the  metallic  state. 

4.  Color  of  Solutions  :  Test  with  Ammonia. — If  a  mineral  con- 
taining copper  is  dissolved  in  an  acid  (usually  nitric  or  hydrochloric 
is  best),  the  solution  will  be  colored  blue  or  green.     On  dilution 
with  water  and  addition  of  ammonia  in  excess,  the  color  becomes 
deep  blue,  owing  to  the  formation  of  a  complex  cuproammonium 
salt.     The  test  is  a  very  good  one  for  copper,  but  the  color  must 
not  be  confounded  with  the  similar  but  much  fainter  blue  given 
by  solutions  containing  nickel  when  similarly  treated. 

a.  To  make  this  test,  dissolve  £  ivory  spoonful  of  malachite  in  a  test- 
tube,  in  3  cc.  of  hydrochloric  acid,  dilute  with  10  cc.  of  water,  and  add 
excess  of  ammonia. 

b.  Dissolve  -J  ivory  spoonful  of  powdered  chalcopyrite  in  a  test-tube,  in 
3  cc.  of  nitric  acid,  boil  until  red  fumes  cease  to  appear,  dilute  with  10  cc. 
of  water,  and  add  ammonia  in  excess.     In  this  experiment,  the  formation  of 
a  precipitate  of  ferric  hydroxide  (p.  87,  §  5)  may  at  first  prevent  the  blue 
color  from  being  seen,  but  by  allowing  the  precipitate  to  settle,  or  better  by 
filtering  it  off,  the  color  shows  distinctly. 

5.  Cuprous  Compounds. — Besides  the  sulphides  and  the  closely 
related  arsenides,  tellurides,  and  selenides,  there  are  very  few  min- 
erals which  are  cuprous  compounds,  cuprite,  Cu30,  being  the  only 
common  one. 

A  quantitative  analysis  is  the  only  means  available  for  proving 
that,  in  combinations  with  sulphur,  copper  exists  in  the  cuprous 
condition.  If  it  is  demonstrated,  for  example,  that  the  atomic 
ratio  of  copper  to  sulphur  is  2  : 1  (see  p.  6),  the  compound  must 
be  Cu2S,  or  cuprous  sulphide. 

To  illustrate  the  reactions  of  cuprous  oxide,  dissolve  an  ivory  spoon- 
ful of  powdered  cuprite  in  3  cc.  of  hot  hydrochloric  acid.  Observe  that  the 
solution  is  nearly  colorless  or  brown,  and  not  blue,  as  with  cupric  com- 
pounds. Cool  the  liquid,  and  then  add  a  large  excess  of  cold  water,  when 


Fluorine  REACTIONS   OF   THE   ELEMENTS.  75 

a  white  precipitate  of  cuprous  chloride,  CuCl,  will  be  thrown  down,  which  is 
only  sparingly  soluble  in  water  and  dilute  acids.  The  precipitate  is  soluble 
in  excess  of  ammonia,  and,  if  oxidation  has  been  avoided,  the  intense  blue 
color  characteristic  of  cupric  compounds  (§  4)  will  not  be  obtained,  although 
some  of  the  copper  may  have  become  changed  to  the  cupric  condition, 
owing  to  the  oxidizing  action  of  the  air. 

Didymium,  Di. — Trivalent.     Atomic  weight,  142. 

Erbium,  Er. — Trivalent.     Atomic  weight,  166. 

The  reactions  of  these  rare  earth-metals  are  given  under  Cerium. 

Fluorine,  F. — Univalent.     Atomic  weight,  19. 

OCCURRENCE. — Fluorine  is  the  characteristic  non-metallic  ele- 
ment of  hydrofluoric  acid,  HF,  and  the  fluorides.  The  number 
of  fluorides  that  have  been  identified  as  minerals  is  not  very 
large,  fluorite,  CaF2 ;  and  cryolite,  ]S"a9AlF6 ,  being  the  most 
important.  Fluorine  is  found  frequently  as  a  constituent  of 
silicates  and  phosphates,  as  in  topaz,  (AlF)2Si04  ;  chondrodite, 
Mg3[Mg(F.OH)]2(SiO4)2;  apatite,  Ca4(CaF)(PO4)3 ;  and  amblygonite, 
Li(AlF)PO4 ,  and,  in  such  compounds,  hydroxyl  and  occasionally 
chlorine  are  isomorphous  with,  and  partially  replace,  the  fluorine. 

DETECTION. — The  etching  of  glass  and  the  formation  of  volatile 
compounds  with  silicon  furnish  the  best  methods  for  the  detection 
of  fluorine. 

1.  Etching  of  Glass. — This  test  is  applicable  only  to  com- 
pounds, other  than  silicates,  which  are  decomposed  by  sulphuric 
acid.  If  without  a  platinum  crucible,  prepare  some  small  paste- 
board trays  or  box-covers  by  placing  them  in  melted  paraffin  and 
allowing  them  to  remain  until  the  paper  is  thoroughly  permeated; 
then,  leaving  several  drops  of  paraffin  in  the  bottom  of  each,  place 
them  to  one  side  on  a  sheet  of  paper  to  cool.  At  the  same  time 
some  pieces  of  window  glass,  larger  than  the  tops  of  the  boxes, 
may  be  coated  with  paraffin  by  dipping  them  in  the  melted 
material  and  allowing  them  to  cool.  To  make  a  test  for  fluorine, 
in  a  platinum  crucible  or  one  of  the  prepared  trays  put  an  ivory 
spoonful  of  the  finely  powdered  mineral  and  3  or  4  drops  of  concen- 
trated sulphuric  acid,  mix  the  two  together  and  cover  with  one  of 


76  REACTIONS    OF    THE    ELEMENTS.  Fluorine 

the  prepared  glass  plates  on  the  under  side  of  which  lines  have 
been  traced  through  the  paraffin  with  some  pointed  instrument. 
The  action  of  sulphuric  acid  on  the  fluoride  liberates  hydrofluoric 
acid,  HF,  which  attacks  the  silica,  Si02 ,  of  the  glass  wherever  it 
is  not  protected  by  the  paraffin;  thus,  4HF  +  SiO,  =  SiF4+  2H3O. 
For  a  successful  experiment  the  etching  should  be  allowed  to  pro- 
ceed for  at  least  one  half  hour,  or  longer  if  the  amount  of  fluorine 
is  small.  The  presence  of  fluorine  is  revealed  by  a  distinct  etch- 
ing of  the  glass,  seen  best  after  warming  the  plate  and  cleaning  off 
the  paraffin  with  a  bit  of  paper  or  cloth. 

Make  the  experiment  with  fluorite,  CaFa ,  when  the  decomposition  with 
sulphuric  acid  may  be  expressed  as  follows :   CaF2  +  H2S04  =  CaS04+  2HF. 

2.  Test  with  Potassium  Bisulphate. — This  test  is  applicable 
only  to   compounds  which  are  decomposed  by  fusion  with  the 
reagent.    Mix  some  finely  powdered  fluoride  with  an  equal  volume 
of  powdered  glass  and  2  or  3  volumes  of  potassium  bisulphate, 
then  put  not  over  \  ivory  spoonful  of  this  mixture  in  a  closed  tube 
of  6  mm.  internal  diameter  and  heat  gently.     The  hydrofluoric  acid 
liberated  by  the  reaction  attacks  the  glass,  4HF  +  SiOa  =  SiF4  + 
2H,O,  and  at  the  place  where  the  water  condenses  a  second  decom- 
position  occurs,  as  follows  :   3SiF4  +  2HaO  =  2H,SiF6  (hydrofluo- 
silicic  acid)  +  SiO,.     The  separated  silica,  SiO., ,  forms  a  white  ring 
in  the  tube,  which  is  volatile  as  long  as  hydrofluosilicic  acid  is 
present,  but  on  breaking  the  tube  just  above  the  fusion  and  wash- 
ing away  the  hydrofluosilicic  acid  from  the  upper  portion  with 
water,  and  then  drying,  the  silica  will  no  longer  be  volatile.     The 
etching  of  the  tube  is  not  a  conspicuous  feature  of  this  test,  but 
the  ring  of  silica  is  very  characteristic,   especially  its  behavior 
before  and  after  washing  with  water. 

3.  Test  with  Sodium  Metaphosphate. — This  test  will  often  be 
found  convenient,  since  it  can  be  applied  to  minerals  which  are  not 
decomposed  ~by  sulphuric  acid.    If  the  finely  powdered  mineral  is 
mixed  with  from  4  to  6  parts  of  sodium  metaphosphate,  transferred 
to  a  bulb  tube  (which  should  not  be  more  than  one  quarter  full) 
and  heated  very  hot,  hydrofluoric  acid  will  be  given  off,  which 
etches  the  glass,  and  deposits  a  ring  of  silica  exactly  as  described 


Fluorine  REACTIONS   OF  THE   ELEMENTS.  77 

-in  §2.  The  test  is  excellent  for  silicates  when  the  proportion  of 
fluorine  is  not  too  small  (less  than  5  per  cent),  but  when  very  small 
quantities  are  to  be  detected  the  method  given  in  §  4  is  preferable. 

Sodium  metaphosphate  may  be  prepared  by  heating  phosphorus  salt  in 
a  platinum  dish  until  ammonia  and  water  are  expelled,  or  a  sufficient 
quantity  for  an  experiment  may  be  quickly  made  by  fusing  beads  of  phos- 
phorus salt  on  platinum  wire,  and  crushing  them  in  a  diamond  mortar.  To 
make  the  experiment,  test  for  fluorine  in  topaz.  The  reaction  with  topaz 
cannot  be  expressed  by  a  definite  equation,  but  in  order  to  illustrate  the 
chemical  principle  involved,  the  simpler  case  of  calcium  fluoride,  CaF2 ,  may 
be  chosen.  CaF2  -f-  NaP03  -f  H20  =  CaNaP04  +  2HF.  It  is  evident  that 
water  orhydroxyl  must  be  present  in  order  to  form  HF,  and  this  may  come 
either  from  hydroxyl  in  the  mineral  or  from  a  trace  of  water  that  was  not 
wholly  driven  out  from  the  sodium  metaphosphate. 

4.-  Precipitation  as  Calcium  Fluoride. — This  test  is  especially 
applicable  for  detecting  small  quantities  of  fluorine  in  silicates. 
The  mineral  is  first  fused  with  sodium  carbonate,  exactly  as 
described  under  silicates  (p.  110,  §  4).  The  fusion  is  then 
pulverized,  treated  in  a  test-tube  with  5  cc.  of  boiling  water,  filtered 
and  washed,  by  which  means  sodium  fluoride  is  obtained  in  solu- 
tion. The  filtrate  is  acidified  with  hydrochloric  acid,  boiled  for  a 
short  time  to  expel  carbon  dioxide,  a  little  calcium  chloride  added 
(some  calcite  dissolved  in  hydrochloric  acid  will  answer),  and  then 
ammonia  in  excess.  The  precipitate  will  contain  calcium  fluoride, 
but  a  precipitate  is  not  a  proof  that  fluorine  is  present,  for  other 
compounds  may  be  thrown  down  at  this  point.  The  precipitate  must 
be  collected  on  a  filter-paper,  washed  well  with  water,  and  ignited  in 
a  crucible  until  the  paper  is  completely  destroyed,  when  the  resi- 
due is  tested  according  to  §  2.  It  is  not  safe  to  test  according  to 
§  1,  for  sometimes  considerable  silica  is  precipitated  with  the 
calcium  fluoride,  and  in  that  case  the  hydrofluoric  acid  will  derive 
silica  from  the  precipitate  instead  of  etching  the  glass. 

5.  Acid  Water  in  a  Closed  Tube.—  Most  minerals  containing 
fluorine  and  hydroxyl  yield  acid  water  in  the  closed  tube,  which 
reddens  blue  litmus-paper,  and  when  the  reaction  is  strong  the 
glass  is  distinctly  etched.  Unless  the  glass  is  etched,  however, 


78  REACTIONS   OF   THE   ELEMENTS.  °°ld 

a  proof  of  the  presence  of  fluorine  must  be  obtained  by  testing 
according  to  some  of  the  foregoing  methods.  In  cases  where 
fluorine  is  isomorphous  with  hydroxyl,  hydrofluoric  acid  will 
sometimes  be  given  off  instead  of  water.  The  acid  then  etches 
the  glass,  forms  a  deposit  of  silica,  and  gives  a  strong  pungent 
smell  at  the  end  of  the  tube.  From  Brazilian  topaz,  for  example, 
which  on  analysis  yields  2.5  per  cent  of  water,  the  hydrogen  is 
mostly  expelled  as  hydrofluoric  acid,  and  there  is  scarcely  any 
indication  of  water,  but,  if  freshly  ignited  lime  or  magnesia  is 
mixed  with  the  mineral  in  the  closed  tube,  the  fluorine  will  be 
retained  and  water  driven  off. 

Gallium,  Ga. — Trivalent.     Atomic  weight,  69.8. 

OCCURRENCE. — This  exceedingly  rare  metal  has  been  found  in  traces  in 
sphalerite  from,  a  few  localities.  It  is  best  detected  by  means  of  the  spark 
spectrum. 

Germanium,  Ge. — Tetravalent.     Atomic  weight,  72.3. 

OCCURRENCE. — This  very  rare  element  has  been  found  in  argyrodite, 
Ag8GeS6;  canfieldite,  Ag8(SnGe)Se,  in  which  tin  and  germanium  are 
isomorphous,  and  in  small  quantity  in  the  rare  mineral  euxeuite. 

DETECTION. — When  argyrodite  is  heated  before  the  blowpipe  on  char- 
coal, germanium  volatilizes,  and  gives  at  first  a  pure  white  coating  of  oxide 
near  the  assay,  which  on  prolonged  heating  moves  farther  out  and  assumes 
a  greenish  to  brownish  but  mainly  lemon-yellow  color.  When  examined 
with  a  lens,  the  coating  presents  a  glazed  or  enamel-like  surface,  while 
scattered  about  on  the  charcoal  near  the  assay,  fused,  transparent  to  milk- 
white  globules  of  germanium  oxide  may  be  detected. 

In  the  closed  tube,  heated  intensely  before  the  blowpipe,  a  slight 
sublimate  of  germanium  oxide  forms,  pale  yellow  when  hot,  becoming 
lighter  on  cooling,  which  with  a  lens  may  be  seen  to  consist  of  numerous 
colorless  to  pale  yellow  globules. 

Germanium  gives  no  reaction  in  the  open  tube.  It  also  imparts  no 
characteristic  color  to  the  flame,  to  the  fluxes,  or  to  its  solution  in  acids. 

Glucinum,  G. — See  Beryllium. 

Goid,  Au. — Univalent  and  trivalent.     Atomic  weight,  197.3. 

OCCURRENCE. — Gold  occurs  usually  in  the  free  state,  that  is,  as  native 
gold,  which  always  contains  some  silver  and  sometimes  traces  of  copper  and 


Cold  REACTIONS   OF  THE   ELEMENTS.  79 

iron.  Native  gold  from  California  generally  contains  about  88  per  cent  of 
the  pure  metal.  Gold  is  found  disseminated  in  small  quantity  in  the  rocks 
of  some  regions,  especially  the  crystalline  schists.  It  is  often  concentrated 
in  veins,  where  it  is  usually  associated  with  quartz  and  pyrite,  and  it 
collects  in  the  sands  and  gravels  which  have  resulted  from  the  disintegra- 
tion of  rocks  and  mountain  masses  that  have  contained  gold.  Owing  to  its 
weak  chemical  affinity  it  does  not  form  very  stable  compounds,  and  the 
only  element  vith  which  it  is  found  in  chemical  combination  in  nature  is 
tellurium.  Petzite,  sylvanite,  krennerite,  and  calaverite  are  tellurides  of 
gold  and  silver,  and  nagyagite  is  a  telluride  and  sulphide  of  lead  and  gold. 

DETECTION. — The  color,  fusibility,  malleability,  high  specific  gravity, 
and  insolubility  in  any  one  acid  are  characters  which  serve  for  the  ready 
detection  of  native  gold. 

As  gold  is  worth  $20.67  a  troy  ounce,  only  a  small  percentage  of  the 
metal  is  needed  to  make  an  ore  very  valuable.  One  per  cent  would  be 
equal  to  291.66  troy  ounces  a  ton,  worth  $6028.  An  ore  containing  yi^  per 
cent  of  gold  would  be  a  rich  one,  and  under  favorable  conditions,  by 
hydraulic  mining,  gravels  are  washed  which  do  not  carry  over  ten  cents 
worth  of  gold  a  ton,  or  less  than  T¥ oVo  o~  °f  one  Per  cent  °f  the  Pure  metal. 

Washing  and  Collecting  in  Mercury. — When  gold  is  present  in  very 
small  quantity,  even  less  than  j^Vo-  °^  one  Per  cent,  it  may  be  usually 
detected  with  great  ease  by  washing  or  panning.  This  process  consists  in 
washing  away  with  water  the  lighter  rock  constituents  (for  the  most  part 
less  than  3  in  specific  gravity)  from  the  gold,  which  varies  from  15  to  19.3 
in  specific  gravity,  according  to  the  proportion  of  silver  it  contains.  In 
order  to  make  the  test,  select  a  sample  of  the  ore  weighing  at  least  a 
pound,  pulverize  it,  and  sift  the  material  through  a  fine  sieve.  At  the  end 
of  the  operation,  care  must  be  taken  to  look  for  particles  of  gold  on  the 
sieve,  for,  being  malleable,  the  particles  are  not  pulverized.  The  powder, 
and  the  metal  left  on  the  sieve,  if  there  is  any,  are  put  in  a  metal  pan,  \  cc. 
of  mercury  is  added,  and  the  pan  is  immersed  in  water  and  agitated  for 
some  time  with  a  rocking  and  twisting  motion,  by  which  means  the  heavy 
gold  goes  rapidly  to  the  bottom,  while  the  lighter  constituents  arrange 
themselves  above  according  to  differences  in  specific  gravity.  From  time 
to  time  the  pan  is  inclined,  and  by  a  little  motion  a  ripple  of  water  is  made 
to  pass  over  the  contents  of  the  pan,  and  carry  off  some  of  the  lighter 
material  from  the  top.  By  continuing  this  process,  the  material  is  finally 
concentrated  so  that  the  gold  is  contained  in  a  very  small  volume,  and  is 
taken  up  by  the  mercury  at  the  bottom  of  the  pan.  To  get  rid  of  the  last 
of  the  rock  material,  the  contents  of  the  pan  are  transferred  to  a  mortar, 
and  ground  in  a  stieam  of  water,  by  which  treatment  the  fine  particles  are 
rapidly  carried  away,  and  finally  only  the  mercury,  with  which  the  gold 
has  amalgamated,  is  left.  In  order  to  obtain  the  gold,  the  mercury  contain- 
ing it  is  dried  with  blotting-paper,  transferred  to  a  shallow  cavity  on  char- 


80  REACTIONS   OF   THE   ELEMENTS.  Helium 

coal,  and  volatilized  by  heating  with  a  small  blowpipe  flame.  The  residual 
gold  may  be  fused  to  a  globule,  using  a  little  borax  or  sodium  carbonate 
when  necessary.  In  order  that  no  ill  effects  may  result  from  the  poisonous 


FIG.  48. 

mercury  vapors,  a  piece  of  wet  blotting-paper  should  be  placed  on  the  char- 
coal, care  being  taken  not  to  wet  the  cavity,  and  another  piece  arched  over 
it  (Fig.  48),  thus  furnishing  a  large  cooling  surface  upon  which  the  mer- 
cury will  condense. 

When  tellurides  are  to  be  tested,  the  powdered  ore  should  be  roasted  and 
then  washed  as  directed  above.  The  roasting  may  be  accomplished  by 
putting  the  ore  in  an  iron  pan  (a  piece  of  sheet  iron  with  the  edges  turned 
up)  and  heating  it  to  faint  redness  in  a  stove  for  some  time.  It  is  w^ll  to 
stir  the  powder  occasionally  with  an  iron  wire. 

Gold  may  be  washed  or  panned  without  the  use  of  mercury.  After 
washing  away  the  lighter  material  the  particles  of  gold  may  often  be  seen 
on  the  bottom  of  the  pan  as  a  "color."  The  metallic  particles  may  be 
collected  in  mercury  and  treated  as  directed  in  the  foregoing  paragraph, 
or  the  concentrated  material  may  be  fused  with,  test  lead  and  borax,  and 
treated  as  directed  under  the  silver  assay,(p.  114,  §  2). 

The  gold  globules  obtained  by  the  foregoing  processes  will  always 
contain  some  silver.  In  order  to  obtain  the  pure  gold,  the  metal  should  be 
fused  with  about  3  times  its  weight  of  pure  silver,  and  then  treated  in  a 
porcelain  dish  or  capsule  with  a  little  warm  nitric  acid,  which  dissolves  the 
silver  and  leaves  the  gold  as  a  brownish-black  powder  or  dark  coherent 
mass.  This  process  of  separating  gold  from  silver  is  called  parting.  The 
finely  divided  gold  may  be  washed  and  finally  collected  and  fused  into  a 
globule  on  charcoal. 

In  exceptional  cases,  platinum  or  some  of  the  metals  of  the  platinum 
group  may  be  found  with  the  gold. 

Helium,  He. — Atomic  weight,  4?. 

OCCURRENCE. — This  element  has  been  recently  discovered,  and 
it  seems  to  be  present  only  in  minerals  containing  uranium,  tho- 
rium, and  yttrium.  It  is  given  off  as  a  gas  when  minerals  con- 
taining it  are  heated  or  are  dissolved  in  sulphuric  acid.  It  is 
detected  by  means  of  the  spark  spectrum. 


Hydrogen  REACTIONS   OF  THE   ELEMENTS.  81 

Hydrogen,  H. — Univalent.     Atomic  weight,  1, 

OCCURRENCE. — Hydrogen  is  found  abundantly  in  nature  in 
combination  with  oxygen  as  water,  and  in  combination  with 
carbon  in  hydrocarbons  (p.  61).  There  are  many  minerals  which 
crystallize  with  a  definite  quantity  of  water,  known  as  water  of 
crystallization.  This  water  constitutes  a  part  of  the  chemical 
molecule,  and  is  always  expressed  in  the  formula.  Thus,  gypsum 
is  CaS04.2H2O,  and  it  contains  21  per  cent  of  H2O;  natron  is 
]N"a2C03.10H20,  and  it  contains  63  per  cent  of  H2O.  Such  min- 
erals are  called  hydrous,  while  those  containing  no  water  are 
anhydrous.  It  is  characteristic  of  water  of  crystallization  that 
it  is  expejled  from  a  mineral  by  very  gentle  ignition,  always  at  a 
temperature  far  below  a  red  heat  and  frequently  below  100°  C. 
Again,  there  are  minerals  containing  the  univalent  radical  liy 
droxyl,  OH,  which  are  known  as  liydr oxides.  For  example 
brucite  is  magnesium  hydroxide,  Mg(OH)a  or  Mg02H2 ,  and  limon- 
ite  is  a  ferric  hydroxide,  Fe403(OH)6.  Hydroxides  when  heated 
yield  water.  Thus,  brucite,  Mg(OH)2  =  MgO  +  H20,  and  limon- 
ite,  Fe4O3(OH)6  =  2Fe2O3  +  3H2O,  but  it  is  characteristic  for  hy~ 
droxides  that  they  must  be  strongly  Jieated,  sometimes  to  a  white 
heat,  before  they  are  decomposed  and  water  is  given  off.  They 
thus  differ  from  compounds  containing  water  of  crystallization. 

Water  of  Crystallization  and  Hydroxyl. 

DETECTION. — Water  is  readily  detected  by  means  of  the  closed- 
tube  reaction. 

1.  Closed-tube  Reaction. — Minerals  containing  either  water 
of  crystallization  or  hydroxyl,  when  heated  in  the  closed  tube, 
yield  water,  which  collects  on  the  cold  walls  of  the  tube.  The  test 
is  very  delicate,  and  usually  pure  distilled  water  is  obtained 
which  is  neutral  to  test-papers. 

a.  To  illustrate  this  reaction,  heat  gypsum  or  brucite  in  a  closed  tube, 
using  fragments  about  2  to  4  mm.  in  diameter,  and  also  make  one  experi- 
ment with  a  minute  fragment,  in  order  to  show  the  small  quantity  of 
water  which  may  be  detected  by  this  means. 


82  REACTIONS   OF  THE   ELEMENTS.  Iodine 

b.  To  illustrate  the  difference  between  water  of  crystallization  and 
hydroxyl,  take  two  closed  tubes  of  equal  size,  place  some  gypsum  in  one 
and  brucite  in  the  other,  and  then,  holding  the  tubes  side  by  side,  pass 
them  back  and  forth  through  a  small  flame  so  as  to  heat  the  ends  slowly 
and  equally.  In  the  tube  containing  gypsurn,  water  is  driven  off  when  the 
temperature  is  scarcely  above  100°  C.,  while  brucite  does  not  yield  water 
until  the  temperature  is  much  higher. 

2.  Acid  Water  in  the  Closed  Tube. — Hydrous  compounds  of 
the  weak  basic  elements,  such  as  iron,  aluminium,  copper,  and 
zinc,  with  volatile  acids,  are  decomposed  on  strong  ignition,  yield- 
ing acid  water  (compare  the  tests  for  Fluorine,  p.  77,  §  5,  and  for 
a  sulphate,  p.  123,  §  3). 

An  excellent  closed-tube  experiment  may  be  made  with  copperas,  FeS04. 
7H30,  which  it  is  well  to  compare  with  that  of  gypsum.  By  heating  very 
gently,  only  neutral  water  is  driven  off  at  first,  but  on  stronger  ignition  the 
FeS04  is  decomposed  into  FeO  and  S03.  A  secondary  reaction  also  sets  in, 
giving  SO,,  which  may  be  detected  by  its  odor.  2FeO  +  S03  =  Fe203  +  S02. 
Both  S03  and  S03,  the  anhydrides  of  sulphuric  and  sulphurous  acids, 
render  the  water  in  the  tube  strongly  acid.  The  strong  basic  elements, 
such  as  sodium,  potassium,  calcium,  strontium,  and  barium,  form  stable 
sulphates,  that  is,  sulphates  which  are  not  decomposed  except  by  intense 
ignition,  and  which  do  not  part  with  their  acid  constituents  in  a  closed 
tube. 

3.  Alkaline  Water  in  the  Closed  Tube. — Minerals  which  yield 
alkaline  water  are  of  rare  occurrence,  but  it  is  sometimes  obtained 
from  those  containing  ammonia. 

Indium,  In. — Trivalent.     Atomic  weight,  113.3. 

OCCURRENCE. — This  exceedingly  rare  metal  has  been  found  in  small 
quantity  in  sphalerite  from  a  few  localities.  Its  presence  is  revealed  by  the 
blue  color  it  imparts  to  non-luminous  flames,  and  these  when  examined 
•with  the  spectroscope  show  an  intense  indigo-blue  and  a  less  intense 
violet  line. 

Iodine,  I. — Univalent.     Atomic  weight,  127. 

OCCURRENCE. — Iodine  is  rarely  met  with,  and  the  only  known  minerals 
containing  it  are  iodyrite,  Agl;  marshite,  CuI;  and  lautarite,  Ca(I03)Q. 

DETECTION. — The  reactions  of  iodine  are  similar  to  those  of  chlorine 
and  bromine  (see  p.  67).  Silver  nitrate  precipitates  silver  iodide,  Agl, 
which  differs  from  silver  chloride  and  silver  bromide  in  being  almost  insol- 


Iron  EEACTIONS   OF  THE   ELEMENTS.  83 

uble  in  ammonia.  With  potassium  bisulphate  in  a  bulb  tube,  either  with 
or  without  pyrolusite,  iodine  is  liberated,  and  may  be  recognized  by  its 
violet  vapors,  or,  if  the  reaction  is  strong,  by  its  crystallization  in  the  tube. 
Silver  iodide  when  heated  in  a  closed  tube  with  galena  yields  a  sublimate 
of  lead  iodide,  which  is  dark  orange-red  when  hot,  changing  to  lemon- 
yellow  when  cold. 

Iridium,  Ir.  —  Trivalent  and  tetravalent.     Atomic  weight,  193. 
Iridium  is  one  of  the  rare  metals  occurring  with  platinum  (see  p.  104). 

Iron,  Fe.  —  Bivalent  in  ferrous  and  trivalent  in  ferric  com- 
pounds. Atomic  weight,  56. 

OCCURRENCE.  —  Iron  is  found  very  abundantly  in  minerals 
(p.  3),  and  those  from  which  most  of  the  metal  of  commerce  is  made 
are  magnetite,  Fe3O4  ;  hematite,  Fe2O3  ;  limonite,  Fe4O3(OH)6  ;  and 
siderite,  FeC03.  Iron  is  found  in  a  great  variety  of  combinations 
with  sulphur  (pyrite,  FeS,  ;  pyrrhotite,  FenS12  ;  and  chalcopyrite, 
CuFeS2),  and  among  the  salts  of  most  of  the  mineral  acids,  sili- 
cates, phosphates,  etc.  It  is  important  to  distinguish  between 
two  classes  of  compounds,  the  ferrous  containing  bivalent,  and 
the  ferric  containing  trivalent,  iron.  Examples  of  ferrous  com- 
pounds are  : 

Fe<g>Si<g\A1 

siderite,  Fe<g>C  =  0;  almandine  garnet,  Fe<o>Si  <Q       ;and 

Fe<g>Si<g>A1 

Li-0 
triphylite, 


and  of  ferric  compounds: 

Ca<g>Si<g\Fe 

hematite,       >  Q  ;  andradite  garnet,  Ca  <  Q  >  Si  <  Q        ;  and 
Fe=0  C)       .  ,O^Fe 

Ca<Q>Sl<O/ 

/Ov 

scorodite,  Fe^  (A  As  =  O.2HaO. 


84  REACTIONS   OF   THE   ELEMENTS.  Iron 

Many  minerals  contain  both  ferrous  and  ferric  iron,  as  magnet- 
ite, Fe,O4  =  FeO  +  FeaO3.  Ferrous  iron  is  very  often  isomor- 
phous  with  the  bivalent  metals,  magnesium,  manganese,  zinc, 
cobalt,  and  nickel;  and  ferric  iron,  with  the  trivalent  metal 
aluminium. 

DETECTION. — The  magnet  will  usually  serve  for  the  detection 
of  iron,  while  more  delicate  tests  can  be  made  with  the  fluxes  or 
in  the  wet  way  with  potassium  ferri-  and  ferrocyanides. 

1.  Test  with  a  Magnet. — Only  a  few  of  the  minerals  contain- 
ing iron  (magnetite  and  pyrrhotite)  are  attracted  by  the  ordinary 
magnet,*  but  many  of  them,  especially  the  sulphides,  oxides,  and 
carbonates,  become  magnetic  after  being  heated  before  the  blow- 
pipe in  the  reducing  flame,  either  on  charcoal  or  in  the  forceps. 
When  thus  heated,  silicates  and  phosphates  become  magnetic 
only  when  they  contain  a  rather  large  percentage  of  iron,  but  the 
test 'is  rendered  more  delicate  if  the  powdered  mineral  is  fused  on 
charcoal  with  about  twice  its  volume  of  sodium  carbonate,  and 
the  resulting  slag  tested  with  a  magnet. 

A  magnet  will  not  attract  a  piece  of  red-hot  iron,  and  frag- 
ments of  minerals  that  have  been  heated  will  not  be  attracted 
until  they  have  become  cold. 

a.  Illustrate  the  above  by  testing  fragments  of  pyrite  and  hematite  with 
a  magnet,  both  before  and  after  heating  in  the  reducing  flame  (compare 
experiments  e  and  f  on  p.  38). 

b.  Test  almandine  garnet  with  a  magnet,  after  fusing  before  the  blow- 
pipe, and  also  test  the  slag  made  by  fusing  the  powdered  mineral  with 
sodium  carbonate  on  charcoal. 

2.  Test  with  the  Borax  Bead. — The  oxides  of  iron  are  soluble 
in  borax,  and  give  colors  which  depend  upon  the  amount  of 
material  in  solution  and  the  state  of  oxidation  of  the  iron.     In  the 
oxidizing  flame,  the  bead  contains  FeaO3 ,  and  with  little  oxide  it 
is  yellow  (amber-colored)  when  hot,  fading  to  nearly  colorless 

*  An  electromagnet,  arranged  with  its  poles  close  together  so  as  to  give  a  con- 
centrated field,  attracts  all  minerals  containing  iron,  unless  the  percentage  of  the 
metal  is  small. 


\ron  REACTIONS   OF   THE   ELEMENTS.  85 

when  cold,  while  with  more  oxide  it  is  brownish-red  when  hot 
and  yellow  when  cold.  In  the  reducing  flame,  the  bead  contains 
FeO,  or  FeO  with  Fea08,  and  the  colors  are  not  so  intense,  with 
Mttle  oxide,  being  pale  green  when  hot,  colorless  when  cold;  and 
'frith  more  oxide,  bottle-green  when  hot,  changing  to  a  paler  shade 
on  cooling. 

3.  Test  with  the  Salt  of  Phosphorus  Bead. — In  the  oxidizing 
Hame  with  little  oxide,  the  c.olor  is  yellow  when  hot,  changing 
to  colorless  when  cold,    and  with  more    oxide,   brownish  -  red, 
changing  through  yellow  to  nearly  colorless.      In  the  reducing 
flame  with  little  oxide,  the  color  is  pale  yellow  when  hot,  fading 
through  pale  green  to  colorless,  and  with  more  oxide,  brownish-red 
when  hot,  changing  on  cooling  to  yellowish-green,  and  finally  to 
nearly  colorless  or,  if  much  oxide  was  used,  to  a  very  pale  violet. 

4.  Special   Tests  for  Ferrous  and  Ferric  Iron. — With  the 
exception    of    the  sulphides    and  a    few  rare    combinations,   if 
minerals    are  dissolved  in  hydrochloric   or  sulphuric  acid,    the 
solution  will  contain  the  iron  in  the  same  state  of  oxidation  as  it 
existed  in  the  original  substance.     For  example,  siderite,  ferrous 
carbonate,  and  hematite,  ferric  oxide,  when  dissolved  in  hydro- 
chloric acid,   yield  ferrous    and  ferric  chlorides,  respectively. 
FeC03  +  2HC1  =  FeCl8  +  H20  +  C03,    and    Fe2O3  +  6HC1  = 
2FeCl,-f  3H20. 

Ferrous  Iron.—  This  may  be  detected  by  adding  potassium 
ferricyanide  to  the  cold,  dilute,  acid  solution,  when  a  deep  blue 
precipitate  of  ferrous  ferricyanide  will  be  formed,  which  does 
not  differ  in  color  from  Prussian  blue.  3FeCl2  +  K6Fe2(CN)12  = 
Fe3Fea(CN)12  +  6KC1. 

In  solutions  containing  ferrous  salts,  potassium  ferrocyanide  produces 
a  pale  bluish-white  precipitate  of  K2Fe2(CN)6 ,  which  by  absorption  of 
oxygen  from  the  air  speedily  acquires  a  blue  color.  Ammonium  sulpho- 
cyanate  causes  no  coloration  in  solutions  of  ferrous  salts,  provided  they  are 
entirely  free  from  ferric  compounds. 

Ferric  Iron.—  This  may  be  detected  by  adding  potassium  f err  o* 
cyanide,  to  the  cold,  dilute,  acid  solution,  when  a  deep  blue 


86  BEACTIONS   OF   THE   ELEMENTS.  Iron 

precipitate  of  ferric  f errocyanide,  or  Prussian  blue,  will  be  formed. 
4FeCl3  +  3K4Fe(CN).  =  Fe4Fe9(CN)18  +  12KC1. 

Addition  of  ammonium  sulphocyanate,  NH4CNS,  produces, 
even  in  dilute  solutions  of  ferric  salts,  an  intense  blood-red  color, 
but  no  precipitate. 

Potassium  ferricyanide  deepens  the  color  of  solutions  containing  ferric 
salts,  but  fails  to  produce  a  precipitate. 

Conversion  of  Iron  from  One  State  of  Oxidation  to  the  Other. — 
a.  Ferrous  iron  may  be  converted  to  ferric  by  boiling  the  hydro- 
chloric acid  solution  with  a  few  drops  of  nitric  acid.  The  reaction 
is  a  rather  complicated  one,  but  in  principle  it  is  simple.  Nitric 
acid  furnishes  oxygen,  and  the  change  may  be  indicated  as  follows , 
2FeCl9  +  2HC1  +  O  =  2FeCl3  +  H2O. 

b.  Ferric  iron  may  be  changed  to  ferrous  by  boiling  the  hydro 
chloric  acid  solution  with  metallic  tin  or  zinc  until  the  yellow  color 
entirely  disappears  (see  p.  26). 

Prepare  a  solution  containing  ferrous  iron  by  dissolving  -J  ivory  spoonful 
of  powdered  siderite  in  5  cc.  of  boiling  hydrochloric  acid. 

a.  To  illustrate  the  reaction  for  ferrous  iron,  take  a  few  drops  of  the 
solution  in  a  clean  test-tube,  dilute  with  cold  water,  and  add  a  little  of  a 
freshly  prepared  solution  of  potassium  ferricyanide,  but  avoid  using  a  large 
excess  of  the  reagent,  for  in  this  case,  owing  to  the  yellow  color  of  the 
solution,  the  precipitate,  when  suspended  in  it,  will  appear  green  instead  of 
blue. 

b.  To  show  the  conversion  of  ferrous  to  ferric  iron,  boil  the  remainder 
of  the  solution  with  a  few  drops  of  nitric  acid,  and  note  the  change  in  color. 

c.  To  illustrate  the  reactions  for  ferric  iron,  take  a  few  drops  of  the 
solution,  oxidized  as  directed  in  the  foregoing  paragraph,  dilute  with  water, 
and  add  a  little  potassium  ferrocyanide,  or  test  a  similar  dilute  solution  with 
ammonium  sulphocyanate.     Save  the  remainder  of  the  solution  for  the 
experiment  under  §  5. 

The  tests  with  potassium  ferricyanide  for  ferrous  iron  and  with  potas- 
sium ferrocyanide  for  ferric  iron  are  exceedingly  delicate,  and  a  very  good 
way  of  applying  them  is  to  take  drops  of  each  reagent  on  a  clean  porcelain 
plate,  and  by  means  of  a  glass  rod  or  tube  to  bring  in  contact  with  them 
drops  of  the  solution  to  be  tested. 

Detection  of  Ferrous  and  Ferric  Iron  in  Insoluble  Minerals, 
especially  Silicates. — Most  minerals  which  are  insoluble  in  acids 


Lead  KEACTIONS   OF   THE   ELEMENTS.  87 

may  be  dissolved  after  they  have  been  decomposed  by  fusion  with 
borax.  To  make  the  test,  take  about  J  ivory  spoonful  of  i^Q  finely 
powdered  mineral  and  three  times  its  volume  of  powdered  bornx- 
glass  in  a  rather  large  closed  tube,  and  fuse  in  a  Bunsen- burner 
flame.  While  hot,  crack  the  glass  about  the  fusion  by  touching 
drops  of  water  to  it,  break  off  the  end,  transfer  to  a  test-tube  con- 
taining 3  cc.  of  hydrochloric  acid  and  boil  for  about  a  minute, 
then  dilute  with  5  cc.  of  water.  Divide  the  solution  into  two 
parts  and  test  one  for  ferrous  iron  with  potassium  ferricyanide, 
the  other  for  ferric  iron  either  with  ammonium  sulphocyanate  or 
potassium  ferrocyanide.  The  tests  are  very  decisive,  and  oxida- 
tion resulting  from  contact  with  the  air  and  reduction  during 
fusion,  which  can  not  be  wholly  avoided,  are  so  trifling  that 
practically  they  may  be  disregarded. 

5.  Precipitation  of  ferric  Iron  with  Ammonia. — Ammonia 
added  in  excess  to  a  solution  containing  ferric  iron  precipi- 
tates the  latter  completely  as  brownish-red  ferric  hydroxide. 
Fed,  +  3NH4OH  =  Fe(OH)3  +  3NH4C1.  The  precipitate  can  be 
readily  filtered,  and  thus  iron  can  be  wholly  removed  from  a 
solution.  Ferrous  iron  is  partially  thrown  down  by  ammonia  as  a 
dirty  green  precipitate,  which  slowly  acquires  a  brown  color, 
owing  to  the  absorption  of  oxygen  from  the  air. 

Lanthanum,  La. — Trivalent.     Atomic  weight,  138. 
The  reactions  of  this  rare  earth-metal  are  given  under  Cerium. 
Lead,  Pb. — Bivalent  and  tetravalent.     Atomic  weight,  207. 

OCCURRENCE. — Lead  is  very  widely  distributed  in  nature  and 
is  found  most  abundantly  in  galena,  PbS.  Among  various  other 
combinations,  the  commonest  are  cerussite,  PbCO3 ;  -anglesite, 
PbSO4 ;  pyromorphite,  Pb4(PbCl)(P04)3 ;  and  wulfenite,  PbMoO4. 
It  is  worthy  of  note  that  silicates  of  lead  are  exceedingly  rare. 

DETECTION. — The  formation  of  metallic  globules  and  a  coating 
of  the  oxide  on  charcoal  are  usually  sufficient  for  the  detection  of 
lead. 

1.  Reduction  on  Charcoal  to  Metallic  .Lead  and  Formation  of 
a  Coating  of  Lead  Oxide. — Lead  is  readily  reduced  from  its 


88  REACTIONS   OF   THE  ELEMENTS.  Lead 

compounds,  and  one  of  the  best  methods  for  its  detection  is  to  mix 
£  ivory  spoonful  of  the  powdered  mineral  with  an  equal  volume  of 
charcoal-dust  and  about  3  volumes  of  sodium  carbonate,  moisten 
to  a  paste  with  water,  transfer  to  a  flat  charcoal  surface  or  a  shal- 
low cavity,  and  heat  before  the  blowpipe  in  a  moderately  strong 
reducing  flame.  By  a  little  manipulation  of  the  blast,  the 
particles  of  lead  may  be  made  to  move  about  and  unite  into  a 
single  globule,  which  appears  bright  when  covered  with  the 
reducing  flame,  but  on  cooling  becomes  dull,  owing  to  a  coating  of 
oxide.  Lead  is,  moreover,  somewhat  volatile,  and  that  portion 
which  passes  off  as  vapor  unites  with  the  oxygen  of  the  air,  and 
deposits  on  the  charcoal  as  a  coating  of  oxide,  which  is  sulphur- 
yellow  near,,  and  bluish- white  distant  from  the  assay.  The  coating 
is  volatile  when  heated  in  either  the  oxidizing  or  reducing  flame. 
The  lead  globule  is  soft  and  malleable,  and  may  be  cut  with  a 
knife  or  flattened  by  hammering  on  an  anvil. 

The  test  may  be  made  with  cerussite  or  other  lead  compound,  and  it 
will  be  well  to  make  a  good-sized  lead  globule  for  use  in  future  experiments. 
The  best  idea  of  the  coating  of  lead  oxide  may  be  obtained  by  removing  the 
globule  to  a  shallow  cavity  in  a  fresh  piece  of  charcoal,  and  heating  for  a 
short  time  before  the  blowpipe  at  the  tip  of  the  blue  cone. 

From  the  foregoing  reaction  on  charcoal,  the  identity  of  lead 
is  seldom  doubtful,  but  the  test  is  sometimes  modified  by  the 
presence  of  other  elements,  while  bismuth  gives  reactions  which 
in  appearance  are  very  similar  to  those  of  lead. 

When  galena  is  roasted  alone  on  charcoal  at  a  rather  high 
temperature,  an  abundant  white  sublimate  is  formed,  resembling 
oxide  of  antimony,  and  consisting  chiefly  of  some  volatile  com- 
bination  of  PbO  and  SO2.  If  roasted  carefully,  however  (p.  39, 
Fig.  41),  at  a  very  low  temperature,  SO2  is  given  off,  and  a  globule 
of  lead  formed,  accompanied  by  the  yellow  coating  of  lead  oxide, 
but  without  much  of  the  white  coating  just  mentioned. 

In  the  presence  of  sulphide  of  antimony,  it  is  recommended  to 
roast  the  powdered  mineral  on  charcoal  with  a  very  small  oxidizing 
flame,  until  the  antimony  is  mostly  volatilized,  and  then  to  add 


Lead  REACTIONS   OF   THE   ELEMENTS.  89 

sodium  carbonate  to  the  residue,  and  heat  in  the  reducing  flame 
so  as  to  form  globules  of  metallic  lead,  which,  however,  will  still 
contain  some  antimony. 

2.  Iodine  Test. — When  a  coating  of  lead  oxide  on  charcoal  is 
moistened  with  a  few  drops  of  hydriodic  acid  and  heated  with  a 
small  flame,  a  volatile  and  very  conspicuous  chrome-yellow  deposit 
of  lead  iodide  is  formed,  which  appears  greenish-yellow  when  there 
is  only  a  thin  coating  of  it  on  the  coal.     A  similar  coating  may  be 
obtained  by  adding  to  the  powdered  mineral  from  2  to  4  volumes 
of  a  mixture  of  potassium  iodide  and  sulphur  (p.  26),  and  heat- 
ing on  charcoal  in  a  small  oxidizing  flame,  or  by  heating  on  a 
gypsum  tablet  as  described  on  p.  17. 

3.  Flame  Coloration. — Lead  compounds,  when  heated  in  a  re- 
ducing flame  before  the  blowpipe,  may  impart  a  pale  azure-blue 
color  to  the  flame,  showing  a  greenish  tinge  in  the  outer  parts. 
If  the  experiment  is  made  in  the  forceps,  special  care  must  be 
taken  not  to  alloy  the  platinum. 

4.  Solution  and  Precipitation  of  Lead. — It  is  best  to  use  dilute 
nitric  acid  (1  part  HNO3  to  2  of  water)  for  the  solution  of  lead 
minerals.     Concentrated  nitric  acid  will  not  answer,  owing  to  the 
insolubility  of  lead  nitrate  in  it.     From  solutions  containing  lead, 
sulphuric  and  hydrochloric  acids  throw  down  lead  sulphate,  PbSO4, 
and  lead  chloride,  PbCl2 ,  respectively,  as  heavy  white  precipitates. 
The  chloride  is  quite  soluble  in  hot  water  and  sparingly  so  in  cold, 
therefore  it  will  not  be  formed  in  solutions  which  are  hot  or  too 
dilute.     It  is  frequently  convenient  to  dissolve  a  lead  mineral  in 
rather  dilute  boiling  hydrochloric  acid,  when,  on  cooling,  most  of 
the  lead  will  crystallize  out  as  lead  chloride. 

Tests  may  be  made  by  dissolving  the  lead  globule  from  §  1  in  about  3  cc. 
of  dilute  nitric  acid,  dividing  into  2  parts,  and  adding  to  one  a  few  drops  of 
dilute  sulphuric  and  to  the  other  a  few  dropjs  of  hydrochloric  acid.  They 
may  also  be  made  with  the  solution  obtained  by  dissolving  some  lead  min- 
eral (cerussite  or  pyromorphite)  in  dilute  nitric  acid. 

In  some  minerals,  it  may  be  found  advantageous  to  test  for 
lead  as  follows:  Decompose  from  3  to  5  ivory  spoonfuls  of  the  fine 


90  REACTIONS   OF   THE    ELEMENTS.  Lithium 

powder  in  a  casserole  with  nitric  acid,  add  2  cc.  of  concentrated 
sulphuric  acid,  and  evaporate  until  the  nitric  acid  is  removed,  and 
white,  choking  fumes  of  sulphuric  acid  commence  to  come  off. 
When  the  dish  becomes  cold,  add  water,  stir  for  some  time,  then 
filter  off  the  insoluble  lead  sulphate,  and  test  some  of  it  according 
to§l. 

Lithium,  Li. — Univalent.     Atomic  weight,  7. 

OCCURKENCE. — This  alkali  metal  is  found  only  in  the  silicates 
and  phosphates,  but  is  not  of  very  rare  occurrence.  The  commonest 
minerals  containing  it  are  lepidolite,  LiK[Al(F.OH)JAl(SiO3)3 ; 
spodumene,  LiAl(SiO3), ;  triphylite,  LiPePO4 ;  lithiophilite, 
XdMnPO4 ;  amblygonite,  Li[Al(F.OH)]PO4 ;  and  some  varieties  of 
tourmaline  and  mica. 

DETECTION. — The  crimson  color  which  lithium  imparts  to  a 
flame  will  usually  serve  for  its  detection.  The  test  may  be  made 
according  to  directions  given  on  p.  35.  The  color  of  a  pure 
lithium  flame  is  nearly  monochromatic,  showing,  when  examined 
with  the  spectroscope,  one  bright  crimson  and  one  very  faint 
yellowish-red  band.  In  testing  minerals,  it  will  be  found  that  the 
appearance  of  the  flame  is  somewhat  modified  by  the  presence  of 
other  substances,  especially  sodium,  which  is  apt  to  occur  in  small 
quantities  with  lithium,  but  usually  its  disturbing  influence  may 
be  overcome  by  the  fact  that  lithium  is  more  volatile  than  sodium. 
When,  therefore,  the  assay  is  first  introduced  into  the  flame,  the 
red  of  lithium  will  show  before  the  yellow  of  sodium,  and  when 
the  flame  is  strongest,  if  the  position  of  the  assay  is  changed  to 
where  the  heat  is  less  intense,  the  yellow  will  disappear  first,  and 
filially  the  red  of  lithium  will  be  distinctly  seen.  Where  the  pro- 
portion of  sodium  is  large,  however,  the  spectroscope  must  be 
resorted  to.  In  testing  silicates,  it  will  often  be  found  ad  van- 
tageous  to  mix  the  assay  with  powdered  gypsum,  and  to  heat  as 
directed  under  potassium  (p.  105,  §  1,  <?).  Colored  glasses  do 
not  assist  very  much  in  the  analysis  of  mixed  flames  containing 
lithium. 


Magnesium  REACTIONS   OF   THE   ELEMENTS.  91 

The  crimson  flame  of  lithium  must  not  be  mistaken  for  that  of 
strontium,  which  it  resembles  very  closely  (p.  116,  §  1). 

Magnesium,  Mg. — Bivalent.     Atomic  weight,  24. 

OCCURRENCE. — Magnesium  is  a  very  common  element  (p.  3), 
being  found  in  a  great  many  silicates,  several  of  which  are 
important  rock-making  minerals;  as  pyroxene,  amphibole,  biotite, 
enstatite,  olivine,  and  serpentine.  It  OCCULTS  also  in  a  variety 
of  other  combinations,  such  as  brucite,  MgO2H2 ;  magnesite, 
MgCO3 ;  dolomite,  MgCa(CO3)a  ;  spinel,  MgAl2O4 ,  etc.  In  the 
majority  of  its  compounds,  some  ferrous  iron  is  isomorphous 
with  the  magnesium. 

DETECTION. — There  are  no  satisfactory  blowpipe  tests  for  mag- 
nesium, and  it  is  best  detected  in  the  wet  way  by  precipitation  as 
ammonium  magnesium  phosphate. 

1.  Precipitation  as  Ammonium  Magnesium  PJiospliate. — From 
a  solution  made  strongly  alkaline  with  ammonia,  sodium  phos- 
phate causes  the  formation  of  a  white  crystalline  precipitate  of 
ammonium  magnesium  phosphate,  NH4MgPO4.6H2O.  Before 
making  the  test  for  magnesium,  however,  it  must  be  ascertained 
that  substances  precipitated  by  ammonia,  ammonium  sulphide 
and  ammonium  carbonate  or  oxalate,  have  been  removed  from 
the  solution,  as  otherwise  a  phosphate  of  some  other  element  might 
be  thrown  down  and  mistaken  for  magnesium;  while  magnesium 
will  not  be  precipitated  by  the  above-mentioned  reagents,  provided 
(a)  that  the  solution  is  sufficiently  dilute,  (b)  that  it  contains  some 
free  mineral  acid,  such  as  hydrochloric  or  nitric,  and  (c)  that  it 
does  not  contain  an  acid  with  which  magnesium  forms  an  insoluble 
combination  (phosphoric,  for  example).  The  manner  in  which  the 
test  is  applied  may  be  illustrated  by  the  following  experiments: 

a.  Dissolve  J  ivory  spoonful  of  brucite,  Mg02H, ,  in  3  cc.  of  hydro- 
chloric acid,  warm  if  necessary,  dilute  with  from  5  to  10  cc.  of  water,  add 
ammonia  in  excess,  and  finally  a  few  drops  of  a  solution  of  sodium 
phosphate. 

1).  Dissolve  ?  ivory  spoonful  of  dolomite,  CaMg(C03)2  (with  probably  a 
trace  of  FeC03),  in  3  cc.  of  boiling  hydrochloric  acid,  add  a  drop  of  nitric 


92  REACTIONS   OF   THE    ELEMENTS.  Manganese 

acid  to  oxidize  the  iron,  then  5  cc.  of  water,  heat  to  boiling,  add  ammonia 
in  excess,  and  filter,  provided  a  precipitate  of  ferric  hydroxide  has  formed 
(p.  87,  §  5).  To  the  filtrate  containing  calcium  and  magnesium  chlorides 
add  ammonium  carbonate  or  oxalate,  which  precipitate  calcium  (p.  60, 
§§  5  and  6),  filter,  and  test  the  filtrate  with  sodium  phosphate. 

For  the  detection  of  magnesium  in  silicates  and  complex 
bodies,  see  p.  110,  §  4. 

2.  Alkaline  Reaction. — A  few  magnesium  minerals  become 
alkaline  after  ignition,  but  the  test,  which  is  made  by  placing  the 
ignited  material  upon  moistened  turmeric-paper,  is  not  very  de- 
cisive nor  satisfactory. 

3.  Test  with  Cobalt  Nitrate. — Some  of  the  white  or  colorless 
magnesium  compounds,  when  moistened  with  cobalt  nitrate  and 
ignited  before  the  blowpipe,  assume  a  faint  pink  color,  but  the 
test  is  neither  very  general  in  its  application  nor  very  satisfactory. 

Manganese,  Mn. — In  minerals,  usually  bivalent,  but  sometimes 
trivalent  and  tetravalent.  Atomic  weight,  55. 

OCCURRENCE. — Manganese  is  very  widely  distributed  in  na- 
ture, small  quantities  of  it,  usually  a  fraction  of  1  per  cent,  being 
found  in  many  minerals  and  in  most  of  the  silicate  rocks.  Some  of 
the  common  manganese  minerals  are  pyrolusite,  MnO2 ;  mangan- 
ite,  MnO(OH) ;  braunite,  Mn2O3  ;  hausmannite,  Mn3O4;  rhodochro- 
site,  MnCO3 ;  rhodonite,  MnSiO, ;  tephroite,  Mn2SiO4 ;  and  lithi- 
ophilite,  LiMnPO4.  It  occurs  rarely  as  sulphide  (alabandite, 
MnS,  and  hauerite,  MnS2). 

DETECTION. — Manganese  can  be  readily  detected  by  means  of 
the  sodium  carbonate  and  borax  beads. 

1.  Test  with  a  Sodium  Carbonate  Bead, — Oxide  of  manganese 
dissolves  in  a  sodium  carbonate  bead,  when  heated  before  the 
blowpipe  in  the  oxidizing  flame,  with  the  formation  of  sodium 
manganate,  Na2MnO4.  The  bead  thus  formed  is  green  when  hot 
and  bluish-green  when  cold.  The  test  is  a  very  delicate  one,  and 
other  substances  are  not  apt  to  interfere  with  it.  In  the  reducing 
flame,  the  manganese  is  reduced  to  MnO  and  the  bead  los^s  its 
color.  • 


Mercury  KEACTIONS   OF   THE   ELEMENTS.  93 

The  experiment  can  be  made  by  dissolving  a  very  little  pyrolusite,  or 
other  mineral  containing  manganese,  in  a  sodium  carbonate  bead  made 
according  to  directions  given  on  p.  24. 

A  similar  test  may  be  made  by  fusing  some  of  the  finely 
powdered  mineral  on  platinum-foil  or  in  a  spoon  with  sodium 
carbonate,  to  which  a  little  potassium  nitrate  has  been  added  in 
order  to  bring  about  the  oxidation.  By  this  means  a  very  small 
quantity  of  oxide  of  manganese,  0.10  per  cent,  may  be  detected  by 
the  bluish-green  color  of  the  fusion. 

2.  TesticitTi  a  Borax  Bead. — Oxide  of  manganese  dissolves  in 
borax,  giving  in  the  oxidizing  flame  a  bead  which  is  opaque  while 
hot,  but  on  cooling  becomes  transparent  and  has  a  fine  reddish- 
violet  or  amethystine  color,  due  to  the  presence  of  a  higher  oxide 
of  manganese.     It  takes  only  a  very  little  manganese  to  give  this 
test,  and  if  too  much  is  added,  the  color  of  the  bead  is  so  intense 
that  it  appears  black.     If  the  bead  is  not  too  strongly  colored,  it 
will  speedily  become  transparent  while  held  in  the  reducing  flamo. 
The  manganese  is  thus  reduced  to  a  lower  oxide,  MnO,  and  the 
bead  is  colorless.     If  the  bead  containing  MnO  is  again  heated  in 
the  oxidizing  flame,    clouds,  which  indicate   the  presence   of  a 
higher  oxide  of  manganese,  soon  make  their  appearance,  and,  on 
cooling,  the  bead  is  reddish-violet.     Other  substances  which  give 
colors  to  borax  may,  of  course,  interfere  with  this  test. 

3.  Tlie  Salt  of  Pliospliorus  Bead.— This  assumes  an  amethys- 
tine color  with  manganese  if  heated  in  the  oxidizing  flame,  but  the 
test  is  not  so  delicate  nor  satisfactory  as  with  borax. 

4.  The  Higher  Oxides  of  Manganese. — There  are  a  number  of 
these    containing    more    oxygen    than   MnO.      They  dissolve  in 
hydrochloric   acid  with   evolution  of  chlorine  gas,  and  some  of 
them,   when  heated,  give  oxygen  gas  (compare  Oxygen,  p.  100, 
§§  1  and  2). 

Mercury,  Hg. — Bivalent  in  mercuric,  and  univalent  in  mercu- 
rous,  compounds.  Atomic  weight,  200. 

OCCURRENCE. — Mercury  is  not  widely  disseminated  in  nature 
and  is  found  in  only  a  few  minerals,  the  one  which  furnishes  most 


94  KEACTIONS   OF   THE   ELEMENTS.  Mercury 

/ 

of  the  metal  of  commerce  being  cinnabar,  HgS.  The  following  are 
all  of  rather  rare  occurrence  :  native  mercury  ;  amalgam,  Ag  with 
Hg  ;  tiemannite,  HgSe  ;  onofrite,  HgSe  with  HgS ;  calomel,  HgCl, 
and  the  varieties  of  tetrahedrite  containing  mercury. 

DETECTION. — The  formation  of  metallic  mercury,  by  heating 
with  sodium  carbonate  in  a  closed  tube,  is  usually  the  most  satis- 
factory test. 

1.  Closed-tube  Tests. — If  the  pulverized  mineral  is  intimately 
mixed  with  about  4  volumes  of  dry  sodium  carbonate,  transferred 
to  a  closed  tube,  covered  with  an  additional  layer  of  sodium  car- 
bonate about  i  cm.  long,  and  heated  in  a  Bunsen-burner  flame,  at 
first  rather  cautiously,  the  mineral  will  be  decomposed  and  metal- 
lic mercury  will  distil  off  and  condense  as  globules  on  the  walls  of 
the  tube.    If  only  a  little  mercury  is  formed,  it  will  appear  as  a  gray 
sublimate  composed  of  minute  globules  which  may  be  made  to 
unite  by  rubbing  with  a  platinum  wire  or  slip  of  paper. 

Mercury  compounds,  when  heated  alone  in  a  closed  tube, 
usually  volatilize  without  decomposition. 

a.  To  make  the  test,  take  about  \  ivory  spoonful  of  cinnabar  and  2  of 
dry  sodium  carbonate,  mix  them  intimately  by  trituration  in  an  agate  mor- 
tar, and  proceed  as  directed  above.     Dry  sodium  carbonate  may  be  had  by 
heating  some  of  the  ordinary  material  below  redness  either  in  a  porcelain 
crucible  or  on  any  clean  metal  surface.     The  reaction  is  as  follows:    HgS  4- 
NaQC03  —  Ilg  +  0  +  C03  +  NaaS.     On  breaking  the  tube  and  placing  some 
of  the  residue  containing  Na2S  on  silver  along  with  a  drop  of  water,  a  test 
for  the  sulphur  may  be  obtained  (p.  120,  §  5). 

b.  Heat  some  cinnabar  alone  in  a  closed  tube,  and  observe  the  black 
sublimate  of  HgS.  which  resembles  the- arsenical  mirror.     Also  observe  that 
no  metallic  mercury  is  formed. 

2.  Open-tube  Reaction.— A.  convenient  way  of  testing  sulphide 
of  mercury  is  to  roast  a  little  of  the  mineral  in  a  rather  large  open 
tube,  when  the  products  formed  are  essentially  metallic  mercury 
and  SO3.      For  success  in  this  experiment,  the  tube  is  at  first 
heated  very  hot  just  above  the  substance,  and  then  the  latter  is 
heated  wry  carefully  and  gradually  so  as  not  to  drive  off  any 
black,  unoxidized  sublimate  of  HgS.     Often  a  slight  non-metallic 
sublimate  forms,  possibly  some  combination  of  oxide  of  mercury 


Molybdenum  REACTIONS   OF   THE   ELEMENTS.  95 

and  SO2 ,  but  if  this  is  driven  up  the  tube  by  heat,  it  is  for  the 
most  part  decomposed,  and  the  resulting  gray  sublimate  will  be 
found  to  consist  of  minute  globules  of  mercury,  which  may  be 
united  by  rubbing  with  a  wire  or  slip  of  paper. 

3.  Precipitation  upon  Copper.— If  a  bit  of  clean  copper  is 
placed  in  a  solution  containing  mercury,  the  mercury  will  deposit 
in  the  metallic  state  upon  the  copper,  and  the  latter  will  then 
appear  as  if  it  had  been  silver-plated. 

Boil  a  mixture  of  powdered  cinnabar  and  pyrolusite  for  a  short  time 
with  hydrochloric  acid,  dilute  with  water,  and  introduce  into  the  cold  solu- 
tion a  copper  coin  or  strip  previously  cleaned  by  dipping  it  into  strong  nitric 
acid  and  washing  with  water.  The  action  of  the  pyrolusite  is  to  liberate 
chlorine  (p.  101,  §  2),  which  is  essential  for  the  solution  of  the  cinnabar. 
The  deposition  of  mercury  upon  the  copper  is  due  to  a  simple  interchange  of 
the  metals.  HgCl,  +  Cu  =  Hg  -j-  CuCl2. 

Molybdenum,  Mo.  —  Tetravalent  and  sexivalent.  Atomic 
weight,  96. 

OCCURRENCE. — Molybdenum  is  found  sparingly  in  nature,  and  mostly  as 
molybdenite,  MoS2 ,  and  wulfenite,  PbMo04. 

DETECTION. — The  character  of  the  test  for  molybdenum  depends  upon 
whether  the  element  occurs  as  sulphide  or  in  an  oxidized  condition.  For 
the  former,  an  oxidation,  and  for  the  latter,  a  reduction  test  is  recommended. 

1.  Roasting  on  Charcoal. — If  a  fragment  of  molybdenite  is  heated  on 
a   flat   charcoal   surface  for   a   considerable   time  in   the   oxidizing  flame, 
there  results,  at  a  short  distance   from   the  assay,  a  coating  of  molybdic 
oxide,  Mo03.     This  is  pale  yellow  when  hot,  almost  white  when  cold,  and 
often  consists  of  delicate  crystals.     Still  nearer  to  the  assay,  the  charcoal 
is  covered  with  a  very  thin,  tarnished,  copper-colored   coating  of  Mo02, 
which  is  seen  best  when  cold  and  by  reflected  light.     The  Mo03  coating  is 
volatile  in  the  oxidizing  flame,  and,  if  touched  for  an  instant  with  a  moder- 
ately hot   reducing  flame,  it   assumes  a  beautiful  ultramarine- blue  color 
(very  characteristic),  due  probably  to  a  combination  of  Mo02  and  MoO.,. 

2.  Roasting  in    the  Open  Tube. — -If  thin   shavings  of  molybdenite  are 
heated  at  a  high  temperature  in  an  open  tube,  a  yellow  sublimate  of  Mo03 
deposits  a  little  above  the  assay,  and  frequently  forms  a  mass  of  delicate 
crystals. 

3.  Flame  Test. — A  fragment  of  molybdenite,  held  in  the  forceps  and 
heated   before  the  blowpipe  at  the  tip  of  the  blue  cone,  impart,*  a  pale 
yellowish-green  color  to  the  flame. 


96  KEACTIONS   OF   THE    ELEMENTS.  Nickel 

4.  Reduction  Test. — In  a  test-tube  take  about  -£  ivory  spoonful  of  finely 
powdered  molybdate  (wulfenite,  PbMoOJ  and  a  scrap  of  paper  not  over 
1  mm.  square,  add  from  3  to  6  drops  of  water  and  an  equal  quantity  of  con- 
centrated sulphuric  acid  and  heat  until  copious  fumes  of  the  acid  begin  to 
come  off,  then,  after  allowing  the  tube  to  become  cold,  add  water  a  drop  at 
a  time.     The  addition  of  the  first  few  drops  of  water  gives  rise  to  a  magni- 
ficent deep-blue  color,  which  quickly  disappears  when  the  quantity  of  water 
added  amounts  to  a  few  cubic  centimeters.    The  exact  nature  of  this  reaction 
is  not  well  understood,  but  it  is  due  presumably  to  a  slight  reducing  action 
caused  by  the  presence  of  the  paper.     It  generally  does  not  succeed  well 
when  only  a  very  minute  quantity  of  mineral  is  tested. 

5.  Reactions  with  the  Fluxes. — The  salt  of  phosphorus  bead  is  best.     If 
a  small  quantity  of  the  oxide  is  dissolved  in  the  bead  in  the  oxidizing  flame, 
the  glass  is  yellowish-green  when  hot,  changing  to  almost  colorless  when 
cold.     In  the  reducing  flame  it  becomes  dirty  green  when  hot,  changing  to 
a  fine  green  on  cooling.     The  tests  with  borax  are  neither  very  satisfactory 
nor  decisive. 

Nickel,  Ni. — Bivalent.    Atomic  weight,  59. 

OCCURRENCE. — Mckel  is  a  comparatively  rare  element,  occur- 
ring most  often  as  a  sulphide  or  arsenide,  and  associated  usually 
with  cobalt  and  iron.  Some  of  its  important  compounds  are 
millerite,  NiS ;  niccolite,  NiAs ;  chloanthite,  NiAs2 ;  gersdorfite, 
NiSAs  ;  penthandite,  NiS  with  FeS  ;  and  genthite,  a  hydrous  sili- 
cate of  nickel  and  magnesium.  Nickel  is  found  with  cobalt  in 
most  of  the  sulphides  and  arsenides  mentioned  under  the  latter 
element,  and  much  of  the  metal  of  commerce  is  obtained  from 
nickeliferous  pyrrhotite,  essentially  FeS,  but  containing  from  1  to 
5  per  cent  of  M  isomorphous  with  the  Fe. 

DETECTION. — The  element  is  usually  detected  by  the  color  its 
oxide  imparts  to  the  borax  bead  in  the  oxidizing  flame. 

1.  Test  with  a  Borax  Bead. — Oxide  of  nickel  dissolves  in  the 
borax  bead,  and  in  the  oxidizing  flame  yields  a  violet  color  when 
hot,  not  unlike  the  color  given  by  manganese,  but  changing  to 
reddish-brown  on  cooling.  By  rather  long  heating  in  a  strong 
reducing  flame,  the  bead  becomes  opaque,  owing  to  the  separation 
of  metallic  nickel,  and  if  the  bead  is  removed  from  the  wire  and 
fused  on  charcoal  in  the  reducing  flame  together  with  a  granule  of 


Nickel  REACTIONS   OF   THE   ELEMENTS.  97 

metallic  tin,  an  alloy  of  tin  and  nickel  is  formed,  and  the  glass 
finally  becomes  colorless  or  nearly  so.  A  small  percentage  of 
cobalt  will  completely  obscure  the  color  of  nickel,  while  a  trace  of 
cobalt  in  the  presence  of  much  nickel  may  be  detected,  as  described 
on  p.  71,  §  1. 

2.  Test  with  a  Salt  of  Phosphorus  Bead. — This  test  for  nickel 
is  not  very  satisfactory.     In  the  oxidizing  flame,  with  little  oxide, 
the  bead  is  reddish  when  hot,  and  becomes  pale  yellow  on  cooling, 
while  with  much  oxide  it  is  brownish-red  when  hot,  becoming 
reddish- yellow  on  cooling.     In  the  reducing  flame  on  platinum 
wire,  the  color  of  the  bead  is  unchanged,  but  if  heated  for  a  long 
time  on  charcoal  with  a  granule  of  tin,  metallic  nickel  is  formed, 
which  alloys  with  the  tin,  and  the  glass  becomes  colorless. 

3.  Test  with  Ammonia. — This  reagent,  when  added  to  a  solu- 
tion containing  nickel,  may  cause  a  slight  precipitate  at  first,  but 
the  precipitate  speedily  dissolves  and  imparts  a  pale  blue  color  to 
the  solution,  which  must  not  be  confounded  with  the  much  deeper 
color  given  by  copper  when  its  solutions  are  treated  in  a  similar 
way. 

4.  Special  Tests  for  NicTcel  and  Cobalt  when   they  Occur  with  Other 
Substances.  —  Treat  some  of  the  powdered  mineral  in  a  casserole  with  acid 
(nitric  is  best  if  the  mineral  is  a  sulphide  or  arsenide),  and  boil  until  solu- 
tion is  effected  and  only  about  5  cc.  of  acid  remain.     Then  dilute  with 
water,  boil,   add  ammonia    in  considerable    excess,  and  filter,  when    the 
nickel  and   cobalt,  or  at  least  the  greater  part  of  them,  will  be  found  in  the 
filtrate  free  from  iron.     Boil  the  filtrate  in  a  casserole,  add  caustic  potash, 
and  continue  the  boiling  until  the  ammonia  salts  are  decomposed,  and  addi- 
tion of  more  potash  does  not  produce  any  additional  smell  of  ammonia.    By 
this  treatment,  nickel  and  cobalt  are  precipitated  as  hydroxides.     These 
should  be  collected  on  a  filter  and  washed  once  or  twice  with  hot  water. 
Test  some  of  the  precipitate  with  a  borax  bead  in  the  oxidizing  flame,  and 
if  it  shows  the  color  of  nickel,  cobalt  is  absent,  or  present  only  in  very  small 
quantity  (compare  p.  71,  §  1).     If,  on  the   other  hand,  the  bead   is  blue, 
indicating   cobalt,  nickel  is  possibly  present,   and  may   be   tested   for  as 

follows : 

Ignite  the  paper  with  the  precipitate  in  a  porcelain  crucible  until  the 
carbon  is  burned  away,  or,  if  there  is  a  large  quantity  of  the  precipitate, 
some  of  it  may  be  placed  on  charcoal  and  dried  out  with  a  blowpipe  flame. 


98  REACTIONS   OF  THE   ELEMENTS.  Niobium 

The  dried  material  is  then  ground  in  a  mortar  with  about  twice  its  volume 
of  metallic  arsenic  and  a  very  little  fused  borax,  transferred  to  a  closed 
tube,  and  heated  gently  at  first,  and  finally  intensely,  before  the  blowpipe, 
until  the  nickel  and  cobalt,  which  have  now  united  with  the  arsenic  to 
form  arsenides,  fuse  into  a  single  globule.  The  glass  is  then  cracked,  and 
the  metallic  globule  freed  as  completely  as  possible  from  slag.  It  is  next 
placed  upon  charcoal  together  with  a  bit  of  borax  glass,  and  heated  at  first 
in  the  reducing  flame  and  then  continuously  in  the  oxidizing  flame,  by 
which  treatment  the  cobalt  is  slowly  oxidized  and  imparts  to  the  borax  its 
characteristic  color.  Sometimes  the  color  is  not  seen  distinctly  until  some 
of  the  fused  borax  is  taken  up  in  the  forceps  and  drawn  out  into  a  thread. 
If  the  quantity  of  cobalt  is  considerable,  it  may  be  necessary  to  remove  the 
globule  from  the  slag  (best  done  by  taking  the  globule  in  the  forceps  and 
plunging  it  while  hot  into  cold  water),  and  fuse  it  with  a  fresh  portion  of 
borax.  As  long  as  cobalt  is  present,  nickel  will  not  oxidize,  and  the  surface 
of  the  bead  remains  bright  while  hot,  but  when  the  cobalt  has  all  been  re- 
moved, the  nickel  commences  to  oxidize,  and  its  oxide  forms  a  crust  over  the 
surface  of  the  bead,  which  is  not  as  readily  dissolved  by  the  borax  as  the 
oxide  of  cobalt.  The  appearance  of  the  bead,  therefore,  indicates  that 
cobalt  is  no  longer  present,  and  if  the  bead  is  removed  and  fused  against 
a  fresh  portion  of  borax,  it  imparts  to  the  latter  the  brown  color  char- 
acteristic for  nickel.  Considerable  experience  in  the  use  of  the  blowpipe  is 
needed  to  carry  out  this  operation  successfully.  Sometimes  a  mineral  may 
be  fused  directly  in  the  reducing  flame,  to  a  globule  of  sulphide  or  arsenide, 
and  then  treated  in  the  oxidizing  flame  with  borax  on  charcoal  as  described 
above.  If  iron  is  present,  it  oxidizes  before  the  cobalt.  Copper,  which  does 
not  interfere  with  the  test,  oxidizes  only  after  the  nickel  has  all  been  re- 
moved. 

For  the  detection  of  small  quantities  of  nickel  in  pyrrhotite,  the  test  as 
given  above  may  be  recommended. 

Niobium,  Nb. — Pentavalent.     Atomic  weight,  94. 

OCCURRENCE. — Niobium,  called  also  columbium,  Cb,  is  almost  invari- 
ably associated  with  tantalum,  and  together  they  constitute  the  acid-form- 
ing elements  of  a  group  of  minerals  known  as  the  niobates  and  tantalates. 
The  two  elements  are  isomorphons  with  one  another,  and  their  compounds 
are  characterized  by  being  unusually  heavy.  Some  of  the  more  common 
minerals  containing  them  are  columbite,  tantalite,  pyrochlore,  microlite, 
fergusonite,  samarskite,  euxenite.  and  polycrase.  Niobium  is,  moreover, 
occasionally  found  in  silicates,  as  wohlerite. 

DETECTION. — Niobium  is  best  detected  by  boiling  an  acid  solution  con- 
taining it  with  metallic  tin,  and  obtaining  a  blue  color  which  is  due  to 
reduction. 


Nitrogen  REACTIONS   OF   THE   ELEMENTS.  99 

1.  Reduction  Test. — As  the  niobates  are  usually  very  insoluble  in  acids, 
they  must  first  be  decomposed,  which   may  be  accomplished  most  conven- 
iently as  follows:  Mix  the  finely  powdered  mineral  with  about  5  times  its 
bulk  of  borax,  moisten  to  a  paste  with  water,  take  up  some  of  the  mixture 
in  a  loop  on  platinum  wire,  and  fuse  at  a  high  temperature  before  the  blow- 
pipe.    Make  two  or  three  of  these  beads,  remove  them  from  the  wire,  crush 
in  a  diamond  mortar,  and  boil  the  powder  with  5  cc.  of  hydrochloric  acid, 
which  should  yield  a  clear  or  nearly  clear  solution.     On  adding  some  gran- 
ulated tin,  and  boiling,  the  blue  color  of  niobium  will  appear,  which  is  not 
readily  changed  to  brown  by  continued  boiling,  and  which  rapidly  disap- 
pears upon  addition  of  water.     The  blue  color  is  due  to  reduction,  but  the 
composition  of  the  compound  which  causes  it  is  not  definitely  known.     If 
titanium  is  present,  the  violet  color  due  to  the  reduction  of  that  element 
appears  before  the  blue  of  niobium.     An  acid  solution  containing  niobium, 
if  treated  in  a  similar  manner  with  metallic  zinc,  becomes  sometimes  mo- 
mentarily blue,  but  the  color  soon  changes  to  brown,  owing  to  reduction  to 
NbCl3.     Tungsten  gives  similar  reduction  tests,  but    may  be  readily  dis- 
tinguished from  niobium  by  a  number  of  reactions  mentioned  under  that 
element. 

2.  Decomposition  ivith  Potassium  Bisulphate. — A  method  that  is  very 
generally  adopted  for  the  decomposition  of  niobates  and  tantalates  is  to  fuse 
the  finely  powdered  mineral  with  from  8  to  10  parts  of  potassium  bisul- 
phate.    The  fusion  is  ordinarily  done  in  a  crucible,  but  it  may  also  be  made 
in  a  test-tube,  since  the  heat  which  is  required  need  not  exceed  faint  red- 
ness and  the  glass  is  not  attacked.    When  the  decomposition  is  complete,  as 
shown  by  the  disappearance  of  dark  particles,  the  tube  may  be  inclined  and 
turned  while  cooling,  causing  the  fusion  to  solidify  as  a  thin  crust  on  its 
sides,  so  that  it  may  be  more  readily  dissolved  on  subsequent  treatment.     It 
is  digested  with  cold  water,  which  requires  considerable  time  (the  application 
of  heat  is  not  recommended),  and  there  is  left  an  insoluble  white  residue 
consisting  of  niobic  and  tantalic  oxides,  while  the  bases  are  in  solution. 
The  insoluble  oxides  are  collected  on  a  filter  and  washed,  and  if  a  portion  of 
them  is  treated  in  a  test-tube  with  hot  concentrated  hydrochloric  acid,  and 
boiled  with  granulated  tin,  the  blue  color  due  to  niobium  may  be  obtained. 

For  the  separation  of  small  quantities  of  tungsten  and  tin  from  the  in- 
soluble niobic  and  tantalic  oxides,  see  p.  126,  §  3. 

3.  Oxide  of  niobium  gives  no  satisfactory  reactions  with  the  fluxes. 

Nitrogen,  N. — Trivalent  and  pentavalent.     Atomic  weight,  14. 

OCCURRENCE. — Nitrogen  is  the  characteristic  non-metallic  ele- 
ment of  nitric  acid,  HNO3 ,  and  of  the  nitrates.  The  simple  ni- 
trates of  the  metals  are  soluble  in  water,  and  are  not  found  as 


100  BEACTIONS   OF   THE   ELEMENTS. 


Oxygen 


minerals  in  regions  where  there  is  a  considerable  rainfall.  In  arid 
regions,  however,  they  may  accumulate  and  be  of  great  commer- 
cial importance,  as  the  sodium  nitrate  deposits  of  Chili  and  Peru. 
The  ammonium  compounds  also  contain  nitrogen,  and  have  already 
been  mentioned  on  p.  43. 

DETECTION  OF  NITRATES.— When  heated  in  a  closed  tube,  or, 
better,  in  a  bulb  tube,  with  potassium  bisulphate,  nitrates  are 
decomposed  and  yield  NO3  gas,  which  may  be  detected  by  its  red 
color  (seen  best  by  looking  into  the  tube  lengthwise),  and  also  by 
its  odor.  Potassium  bisulphate  may  be  omitted  in  testing  nitrates 
of  the  heavy  metals,  for  they  are  so  readily  decomposed  that  NO9 
gas  is  given  off  even  on  moderate  ignition. 

Osmium,  Os. — See  the  platinum  metals,  p.  104. 
Oxygen,  O. — Bivalent.     Atomic  weight,  16. 

OCCURRENCE. — Oxygen  is  the  most  abundant  element  in  the 
crust  of  the  ea^rth  (p.  3).  With  the  exception  of  the  native  ele- 
ments, the  sulphides,  fluorides,  and  hajogen  salts,  oxygen  is 
present  in  all  minerals.  Many  elements  unite  with  oxygen  in 
varying  proportions;  those  containing  the  smallest  quantity  of 
oxygen  are  called  lower  oxides,  or  ous  compounds  (FeO  ~  ferrous 
oxide),  and  those  with  more  oxygen,  higher  oxides,  or  ic  com- 
pounds (Fe20s  =  ferric  oxide). 

DETECTION. — Usually  no  direct  test  is  made  for  oxygen,  but  if 
a  mineral  is  determined  to  be  a  salt  of  some  oxygen  acid,  as  car- 
bonic or  silicic,  which  may  be  readily  done,  it  must  contain  oxygen  ; 
while,  on  the  other  hand,  if  it  is  a  sulphide  or  chloride,  it  probably 
will  not  contain  oxygen.  However,  oxy sulphides,  oxy chlorides, 
and  oxyfluorides,  although  rare,  are  known,  as  are  also  chlorides 
and  fluorides  containing  water  of  crystallization.  For  some  of  the 
higher  oxides,  the  closed-tube  test,  or  the  liberation  of  chlorine 
when  dissolved  in  hydrochloric  acid,  may  be  applied. 

1.  Closed-tube  Reaction. — Some  of  the  higher  oxides,  when 
heated  in  a  closed  tube,  yield  oxygen  gas,  which  is  colorless  and 


Phosphorus  REACTIONS   OF   THE    ELEMENTS.  101 

odorless,  but  may  be  detected  by  burning  a  piece  of  charcoal 
in  the  tube. 

Place  some  fragments  of  pyrolusite,  Mn02,  in  the  bottom  of  a  closed 
tube,  and  a  little  above,  a  sliver  of  charcoal  (compare  Fig.  45,  p.  62) ;  then 
heat  the  charcoal  alone,  and  observe  that  although  it  gets  red  hot,  it  does 
not  burn,  owing  to  the  limited  supply  of  air  in  the  tube.  Keeping  the 
charcoal  hot,  apply  heat  to  the  pyrolusite,  and  as  soon'  as  oxygen  com- 
mences to  be  given  off,  the  charcoal  will  burn  brightly,  and  continue  to  do 
so  as  long  as  oxygen  is  supplied  by  the  mineral.  The  reaction  is  3Mn02  = 
Mn304  +  20. 

2.  Liberation  of  Chlorine. — When  some  of  the  higher  oxides 
are  dissolved  in  hydrochloric  acid,  chlorine  gas  is  liberated,  which 
may  be  recognized  by  its  peculiar  odor  and  bleaching  action,  while 
ordinary  oxides  when  similarly  treated  do  not  set  chlorine  free. 
These  differences  are  illustrated  by  the  following  equations: 

Mn02  +  4HC1  =  MnCla  +  2H2O  +  201. 
Fe2O3  +  6HC1  =  2FeCl8  +  3H2O. 

Whether  chlorine  is  liberated  or  not  depends  upon  the  charac- 
ter of  the  metal.  The  oxygen  of  the  oxide  and  hydrogen  of  the 
acid  unite  to  form  water,  and  if  the  chlorine  thus  available  is  more 
than  sufficient  to  satisfy  the  valence  of  the  metal,  the  excess  will 
be  liberated. 

Treat  one  ivory  spoonful  of  finely  powdered  pyrolusite,  Mn02,  in  a  test- 
tube  with  5  cc.  of  hot  hydrochloric  acid.  Observe  the  odor  of  the  escaping 
gas,  and  also  bleach  a  piece  of  moistened  litmus-paper  by  holding  it  for  a 
short  time  within  the  test-tube. 

Palladium,  Pd. — See  the  platinum  metals,  p.  104. 
Phosphorus,  P. — Pentavalent  (usually).     Atomic  weight,  31. 

OCCURRENCE. — Phosphorus  is  the  characteristic  non-metallic 
element  of  phosphoric  acid,  H3PO4 ,  and  its  salts,  the  phosphates. 
Although  a  great  many  phosphates  are  known,  the  majority  of 
them  are  rare  minerals,  and  many  of  them  are  isomorphous  with 
arsenates  and  vanadates.  The  following  will  serve  as  illustrations : 


102  REACTIONS    OF   THE    ELEMENTS.  Phosphorus 

apatite,  Ca4(CaF)(PO4), ;  triphylite,  Li(Fe,Mn)PO4;  and  vivianite, 
Fe3(P04)2.8H20. 

DETECTION. — Ammonium  molybdate  is  the  best  reagent  for  the 
detection  of  phosphates,  but  the  flame  coloration  or  the  reduction 
test  with  magnesium  may  be  used. 

1.  Test   with  Ammonium  Molybdate. — When  a    nitric    acid 
solution  of  a  phosphate  is  added  to  a  solution  of  ammonium  mo- 
lybdate,   according  to  the    directions    given    beyond,   a  yellow 
precipitate    of    ammonium    pliospTiomolybdate,     approximately 
Mo10(NH4)2P034.l^H20,     is    thrown    down,     and     furnishes     an 
exceedingly  delicate  test.      Only  a  little  of  the  phosphate  solu- 
tion should  be  added  to  the  ammonium  molybdate  at  first,  since 
the  precipitate  may  not  form  if  an  excess  of  phosphoric  acid  is 
present.     The  precipitation  should  take  place  in  a  cold  or  only 
slightly  warmed  solution,  for  if  heated  to  boiling,  other  things, 
especially  a  corresponding  arsenic  compound  might  be  throAvn 
down  and  mistaken  for  the  phosphate  precipitate.     If  the  mineral 
is  insoluble  in  nitric  acid,   it  may  be  first  fused  in  a  sodium 
carbonate  bead  and  then  dissolved  in  this  acid.      An  acid  other 
than  nitric  may  be  used  for  dissolving  the  mineral,  but  in  that 
case  it  is  best  to  nearly  neutralize  the  excess  of  free  acid  with 
ammonia,  before  adding  the  solution  to  the  ammonium  molybdate. 
When  applying    this  test,   it  is  recommended  to  follow  quite 
closely  the  details  of  the  experiment  as  given  below. 

Dissolve  i  ivory  spoonful  of  apatite  in  about  3  co.  of  warm  nitric  acid, 
and  pour  a  few  drops  of  the  solution  into  another  test-tube  containing 
about  5  cc.  of  ammonium  molybdate,  when,  after  standing  a  few  minutes 
in  the  cold,  the  yellow  precipitate  will  make  its  appearance. 

2.  Flame    Test. — Many  phosphates  when  heated    before  the 
blowpipe  impart  a   pale  bluish-green  color  to   the  flame,  while 
others  often  show  the  reaction  if  moistened  with  concentrated 
sulphuric  acid  and  then  heated.      The  color,  although  not  very 
marked,  is  often  sufficient  for  the  identification  of  a  phosphate 
(compare  p.  136). 


Platinum  REACTIONS   OF  THE    ELEMENTS.  103 

The  experiment  may  be  made  with  fragments  of  wavellite,  A16P4019. 
12H20,  or  apatite.  In  case  the  latter  mineral  is  used,  it  is  necessary  to 
moisten  the  fragment  with  sulphuric  acid,  and  then  the  color  is  distinct  for 
only  a  short  time. 

3.  Reduction  with  Metallic  Magnesium. — Phosphates  of  the 
alkalies  and  alkaline  earths,  when  strongly  ignited  in  a  closed 
tube  with  magnesium,  are  reduced,  with  the  formation  of  a 
phosphide.  This,  when  moistened  with  water,  gives  the  disagree- 
able odor  of  phosphuretted  hydrogen,  PH3,  somewhat  like  the 
garlic  odor  of  arsenic.  When  phosphates  of  aluminium  and  the 
heavy  metals  are  to  be  tested,  it  is  best  to  fuse  the  powdered 
mineral  with  2  parts  of  sodium  carbonate  on  charcoal,  to  remove 
and  grind  up  the  fused  mass,  and  then  to  ignite  the  powder  with 
magnesium. 

The  experiment  may  be  made  with  apatite  or  wavellite.  In  the  latter 
case,  however,  the  mineral  should  first  be  fused  with  sodium  carbonate. 

Take  a  piece  of  magnesium  ribbon  about  25  mm.  long,  roll  or  fold  it  up 
into  a  compact  mass,  and  drop  it  into  a  closed  glass  tube.  Next  add  the 
finely  powdered  phosphate,  tap  the  tube  so  as  to  bring  the  powder  as  much 
as  possible  in  contact  with  the  magnesium,  and  ignite  very  strongly  with  a 
blowpipe  flame,  being  careful  to  hold  the  tube  in  such  a  manner  that,  if  an 
explosion  should  occur,  the  contents  would  not  be  shot  out  into  the  face. 
Crack  off  the  end  of  the  tube  by  dropping  water  upon  it  while  it  is  still 
hot,  moisten  the  contents  with  a  few  drops  of  water,  and  observe  the  odor 
of  the  phosphuretted  hydrogen;  or,  after  allowing  the  tube  to  become  cold, 
introduce  a  drop  or  two  of  water,  and  observe  the  odor  at  the  end  of  the 
tube. 

Platinum,  Pt. — Bivalent  and  tetravalent.     Atomic  weight,  195. 

OCCURRENCE. — Platinum  is  found  native,  but  it  then  always  contains 
some  iron  and  traces  of  other  metals  belonging  to  the  platinum  group. 
The  only  mineral  containing  platinum  in  chemical  combination  is  sperrylite, 
PtAsa. 

DETECTION. — The  color,  high  specific  gravity,  infusibility,  and  insolu- 
bility in  any  single  acid,  are  properties  which  serve  for  the  identification  of 
platinum.  When  the  metal  occurs  in  sand,  it  may  be  concentrated  by 
washing  as  described  under  gold,  but  without  using  mercury.  For  a  more 
definite  test  for  platinum,  it  is  recommended  to  fuse  the  metal  in  a  cavity 
on  charcoal  with  some  test-lead,  using  borax,  if  necessary,  to  take  up 


104  REACTIONS   OF  THE   ELEMENTS.  Platinum 

impurities.  The  metallic  globule,  freed  from  slag  by  hammering,  is  then 
treated  with  dilute  nitric  acid  (1HN03  :  2HaO),  which  dissolves  everything 
but  the  platinum  metals  and  gold,  and  these  are  then  collected  upon  a 
filter-paper,  washed,  and  ignited.  The  finely  divided  platinum  thus 
obtained  dissolves  readily  in  aqua  regia,  giving  a  reddish-yellow  solution 
containing  hydrochlorplatinic  acid,  H2Pt016,  which  should  be  evaporated 
nearly  to  dryness,  at  a  moderate  heat,  treated  with  hydrochloric  acid,  and 
again  evaporated.  It  should  be  finally  taken  up  with  a  little  water,  filtered 
if  necessary,  and  added  to  a  concentrated  solution  of  ammonium  chloride, 
when  a  yellow  precipitate  of  ammonium  platiuic  chloride,  (NH4)2PtCl6> 
will  be  thrown  down.  The  precipitate,  if  collected  upon  a  filter,  washed 
with  alcohol,  and  ignited,  yields  a  gray  platinum  sponge,  containing  often 
some  other  metals  of  the  platinum  group.  Gold,  if  present,  will  be  in  the 
filtrate. 

The  Rarer  Metals  of  the  Platinum  Group. 

Ruthenium,  Ru.— Atomic  weight,  101.5. 
Rhodium,  Kh. — Atomic  weight,  103. 
Palladium,  Pd. — Atomic  weight,  106.5. 
Osmium,  Os. — Atomic  weight,  190.8. 
Iridium,  Ir. — Atomic  weight,  193.1.' 

OCCURRENCE. — All  the  above  metals  are  found  in  small  quantity  in 
native  platinum.  Iridium  and  palladium,  containing  some  platinum  and 
traces  of  the  other  platinum  metals,  are  found  native.  Iridosmine  is  a  mix- 
ture consisting  chiefly  of  iridium  and  osmium.  Laurite  is  essentially  RuS2. 

DETECTION. — The  analysis  of  the  platinum  metals  is  one  of  the  difficult 
problems  of  analytical  chemistry  for  which  advanced  works  on  the  subject 
should  be  consulted.  A  few  special  tests,  however,  will  be  given. 

Osmium  is  characterized  by  a  volatile  oxide,  Os04,  which  has  an 
Bxceedingly  penetrating  and  disagreeable  odor,  somewhat  resembling  bro- 
mine. The  vapors  are  poisonous  and  should  not  be  breathed  too  freely. 
The  odor  may  be  obtained  by  heating  the  powdered  mineral  in  an  open 
tube,  and  a  very  characteristic  test  may  be  made  by  bringing  the  upper  end 
of  the  tube  within  a  Bunsen-burner  flame,  so  that  the  osmic  oxide  will  pass 
into  the  latter,  which  will  become  luminous,  owing  to  the  reduction  of  the 
osmic  oxide  and  to  the  glowing  of  the  finely  divided  metallic  osmium.  The 
odor  of  osmium  is  also  obtained  when  the  finely  divided  mineral  is  oxidized 
by  fusing  in  a  bulb  tube  with  sodium  or  potassium  nitrate. 

Iridium  and  iridosmine  are  characterized  by  their  hardness  (6-7)  and 
insolubility  in  acids,  even  aqua  regia  failing  to  dissolve  them.  Iridium  is 
partially  oxidized  by  fusion  with  sodium  nitrate  (this  may  be  done  in  a 


Potassium  REACTIONS   OF   THE   ELEMENTS.  105 

bulb  tube),  and  the  fused  mass  when  boiled  with  aqua  regia  yields  a  deep 
red  to  reddish-black  solution. 

Native  palladium  exhibits  a  bluish  tarnish,  which  is  lost  by  heating  in 
the  reducing  flame,  the  color  becoming  like  that  of  platinum,  but  is 
regained  by  heating  moderately  in  the  air  (best  in  an  open  tube).  When  a 
piece  is  flattened  on  an  anvil  to  expose  a  maximum  surface,  and  fused  with 
potassium  bisulphate,  the  metal  is  oxidized  and  dissolved  to  some  extent. 
On  soaking  out  the  fusion  in  water,  and  adding  a  very  small  crystal  of 
potassium  iodide,  a  black  precipitate  of  palladous  iodide  is  formed,  which 
dissolves  in  a  large  excess  of  potassium  iodide,  giving  a  deep  wine-red  color. 

Potassium,  K. — Univalent.     Atomic  weight,  39.1. 

OCCURRENCE. — Potassium  is  a  very  abundant  element,  and, 
although  its  simple  salts  are  soluble  in  water,  it  occurs  in 
insoluble  combinations  in  many  silicates.  Orthoclase,  KAlSi3O8 , 
is  one  of  the  most  abundant  minerals  in  the  crust  of  the  earth. 
The  most  important  minerals  for  the  production  of  potassium 
compounds  are  certain  soluble  chlorides  (sylvite,  carnalite),  which 
are  found  in  connection  with  deposits  of  rock  salt. 

DETECTION. — Flame  coloration  furnishes  the  most  convenient 
means  of  testing  for  potassium,  and,  where  this  test  cannot  be 
applied,  precipitation  as  potassium  platinic  chloride  may  be 
resorted  to. 

.  I.  Flame  Test. — Volatile  potassium  compounds  color  the  flame 
pale  violet,  and  the  test  may  be  made  by  introducing  the  sub- 
stance, held  in  the  forceps  or  in  a  loop  on  platinum  wire,  into  the 
hottest  part  of  the  Bunsen-burner  or  blowpipe  flame.  The  flame 
color  is  not  very  strong  and  is  easily  obscured  by  other  elements, 
especially  sodium,  but  by  viewing  it  through  blue  glass  of  suffi- 
cient thickness,  the  disturbing  colors  may  be  absorbed,  and  the 
potash  flame  will  be  distinctly  seen  of  a  violet  or  purplish-red 
color,  depending  upon  the  depth  of  color  of  the  glass. 

«.  Take  up  some  sylvite,  KC],  in  a  small  loop  on  platinum  wire,  intro- 
duce it  into  a  Buusen-burner  flame,  and  observe  the  color.  Also  examine 
the  flame  through  various  thicknesses  of  blue  glass. 

I.  Add  a  little  sodium  chloride  to  the  potassium  chloride,  and  repeat  the 
foregoing  experiment. 

c.  In  testing  silicates  from  which,  under  ordinary  conditions,  the  potas- 


106  REACTIONS   OF   THE    ELEMENTS.  Potassium 

slum  is  not  readily  volatilized,  the  following  method  will  be  found  very 
useful:  Mix  the  finely  powdered  mineral  with  an  equal  volume  of  powdered 
gypsum,  and  having  heated  a  platinum  wire  until  it  gives  no  color  to  the 
flame,  touch  the  end  of  it  to  a  drop  of  water  and  then  to  the  mixture,  so  as 
to  take  up  a  little  of  the  latter.  Introduce  this  carefully  into  the  hottest 
part  of  a  Bunsen-burner  flame,  and  observe  the  color,  making  use  of  blue 
glass  to  absorb  the  yellow  resulting  from  sodium,  which  is  almost  sure  to  be 
present,  in  traces  at  least,  with  potassium.  Gypsum,  when  fused  with  the 
mineral,  forms  calcium  silicate  and  potassium  sulphate,  and  the  latter,  when 
it  volatilizes,  imparts  the  color  to  the  flame.  Instead  of  a  straight  wire,  a 
small  loop  may  be  used  for  taking  up  the  mixture,  but  it  is  necessary  to 
have  a  heat  sufficiently  intense  to  fuse  the  minerals  together  and  liberate 
the  potassium  sulphate.  The  test  is  quite  delicate. 

2.  Alkaline  Reaction. — With  the  exception  of  the  silicates, 
phosphates,  borates,  and  salts  of  a  few  rare  acids,  the  potassium 
compounds    become  alkaline   upon    intense   ignition   before  the 
blowpipe.     The  test  is  not  so    satisfactory  as  that  made  with 
minerals  containing  other  alkalies  and  alkaline  earths. 

3.  Precipitation  as  Potassium  Platinic  Chloride. — If  hydro- 
chlorplatinic    acid,  H2PtCl6 ,  is   added  to  a  rather  concentrated, 
neutral,  or  slightly  acid  solution  containing  potassium,  a  yellow 
crystalline  precipitate  of  potassium  platinic   chloride,    KQPtCl6, 
will  be  formed,  which  furnishes  an  excellent  means  for  detecting- 
potassium.      The  precipitate  is  sparingly  soluble  in   water,  and 
almost  absolutely  insoluble  in  alcohol.      Ammonium  compounds 
yield  a  similar  precipitate,  (NH4)2PtCl6. 

a.  In  order  to  make  the  test,  dissolve  a  little  sylvite,  KC1,  in  a  few  drops 
of  water,  and  then  add  a  few  drops  of  hydrochlorplatinic  acid. 

Z>.  To  adapt  the  test  to  insoluble  silicates,  proceed  as  follows:  Fuse  the 
powdered  mineral  with  sodium  carbonate,  as  described  in  detail  under 
silicates  (p.  110,  §  4).  Pulverize  the  fused  mass,  treat  it  in  a  test-tube  with 
a  little  hydrochloric  acid,  evaporate  to  dryness,  and  after  cooling  add  about 
2  cc.  of  water  and  boil.  Next  add  an  equal  volume  of  alcohol,  filter  through 
a  small  paper,  and  add  a  few  drops  of  the  hydrochlorplatinic  acid  solution 
to  the  filtrate  in  order  to  precipitate  the  potassium. 

Rhodium,  Rh. — See  the  rare  metals  of  the  platinum  group,  p.  104. 
Rubidium,  Kb. — Univalent.     Atomic  weight,  85.5. 
OCCURRENCE. — This  rare  alkali  metal  is  found  very  sparingly  together 
with  caesium  in  some  varieties  of  lepidolite. 


Silicon  REACTIONS   OF  THE    ELEMENTS.  107 

DETECTION. — Rubidium  is  very  similar  to  potassium,  and  forms  an 
insoluble  platinic  chloride,  Rb2PtCl6.  Examination  with  a  spectroscope 
is  needed  for  its  identification. 

Selenium,  Se. — Bivalent  and  sexivalent.     Atomic  weight,  79. 

OCCURRENCE. — This  rare  element  is  found  usually  in  combination  with 
the  metals,  as  selenides;  clausthalite,  PbSe;  tiemannite,  HgSe,  etc.,  which 
are  analogous  to  sulphides. 

DETECTION. — When  a  substance  containing  selenium  is  heated  before 
the  blowpipe  on  charcoal,  a  curious  odor  may  be  observed  which  is  de- 
scribed by  Berzelius  as  similar  to  that  of  radishes  and  also  of  decaying 
radishes.  It  is  impossible  to  describe  this  odor,  but  only  a  few  trials  are 
necessary  to  render  it  familiar,  and  it  is  so  pronounced  and  characteristic 
that  a  very  minute  quantity  of  selenium  may  be  detected  by  means  of  it.. 
If  the  selenium  is  present  in  considerable  quantity,  it  volatilizes  as  a  brown- 
ish smoke,  and  some  of  it  deposits  at  a  little  distance  from  the  assay  as  a 
silvery  coating  of  oxide,  Se02 ,  which  may  have  an  outer  border  of  red, 
owing  to  admixture  of  finely  divided  selenium.  If  the  coating  is  touched 
with  the  reducing  flame,  the  selenium  volatilizes,  and  imparts  a  magnificent 
azure-blue  color  to  the  flame.  This  is  an  extremely  delicate  and  character- 
istic test. 

In  the  open  tube,  selenium  yields  a  white  oxide,  Se02,  which  usually 
crystallizes  in  radiating  prisms  on  the  sides  of  the  glass,  and  is  reddened  by 
an  admixture  of  finely  divided  selenium.  The  sublimate  is  volatile,  and, 
if  driven  up  the  tube,  it  may  be  made  to  give  a  beautiful  blue  color  if  the 
tube  is  held  so  that  the  vapors  at  the  end  pass  into  the  reducing  part  of  a 
Bunsen-burner  flame. 

In  the  closed  tube,  selenium  volatilizes  from  some  of  its  compounds, 
and  condenses  as  black  globules  fused  against  the  glass,  but  where  the 
globules  are  very  minute,  they  transmit  some  light  and  cause  the  thinnest 
part  of  the  sublimate  to  appear  red  or  brown.  Owing  to  the  air  in  the 
tube,  a  little  oxide,  Se02,  may  form,  which  crystallizes  on  the  glass  above 
the  selenium. 

Silicon,  Si. — Tetravalent.     Atomic  weight,  28. 

OCCURRENCE. — Next  to  oxygen,  silicon  is  the  most  abundant 
element  in  the  minerals  which  constitute  the  crust  of  the  earth 
(p.  3).  In  combination  with  oxygen,  it  forms  the  very  common 
mineral,  quartz,  SiO2,  and  it  is  the  characteristic  non-metallic 
element  in  the  silicates,  or  salts  of  silicic  acid.  Silicates  are  very 
numerous,  and  salts  of  several  kinds  or  types  of  silicic  acids  are 
recognized,  the  most  important  of  which  are  as  follows: 


108  REACTIONS   OF   THE   ELEMENTS.  Silicon 

Orthosilicic  acid,     H4SiO4. 

Metasilicic  acid,       H4Si2O6  =  2H2SiO,. 

Trisilicic  acid,          H4Si3OB. 

Tetrasilicic  acid,      H4Si4O10  =  2H2Si2O5. 

The  acids,  written  as  above  in  a  progressive  series,  differ  from 
one  another  by  addition  of  SiO2.  There  are  no  methods  for  deter- 
mining just  what  kind  of  silicic  acid  is  contained  in  any  given 
silicate  except  quantitative  chemical  analyses  from  which  the 
ratio  between  the  silica  and  the  metals  may  be  calculated  (p.  6). 
For  example,  in  forsterite,  Mg :  Si  =  2 : 1,  and,  Mg  being  biva- 
lent, the  formula  must  be  Mg2SiO4,  a  salt  of  orthosilicic  acid.  In 
orthoclase,  K :  Al :  Si  =  1  :  I  :  3,  and  potassium  being  univalent 
and  aluminium  trivalent,  the  formula  is  KAlSi3O8.  In  the  major- 
ity of  cases,  the  empirical  formulae  of  the  silicates  have  been 
determined  with  a  fair  degree  of  accuracy,  and  most  of  them  have 
been  found  to  correspond  to  the  few  types  of  acids  already  men- 
tioned, the  orthosilicates  and  metasilicates  being  the  commonest, 
'i'he  formulae  of  some  silicates,  however,  and  among  them  a  few 
of  the  common  ones,  are  uncertain.  The  true  constitution  of  the 
silicates,  that  is,  their  structural  formulae  or  the  manner  in  which 
the  atoms  are  united  to  one  another,  is  uncertain,  and  largely  a 
matter  of  conjecture.  It  has  been  found  that  the  metals  sodium, 
potassium,  calcium,  magnesium,  ferrous  and  ferric  iron,  and 
aluminium,  are  of  very  common  occurrence  in  the  silicates,  and 
that  orthosilicates  are  more  soluble  in  acids  than  metasilicates 
and  polysilicates. 

DETECTION. — The  surest  method  for  the  identification  of  a 
silicate  is  to  get  the  mineral  in  solution  in  an  acid,  and  obtain 
gelatinous  silica  by  evaporation.  The  residue  or  skeleton  of 
silica  obtained  in  the  salt  of  phosphorus  bead  furnishes  a  simple 
but  not  very  delicate  test. 

1.  Formation  of  a  Jelly. — When  a  silicate  is  dissolved  in 
acid  the  solution  may  be  regarded  as  containing  free  silicic  acid, 
possibly  H4SiO4,  and,  upon  evaporation,  there  comes  a  point 
when  the  latter  can  no  longer  remain  in  solution,  but  yields  a 


Silicon  REACTIONS   OF  THE    ELEMENTS.  109 

gelatinous  mass.  If  the  evaporation  is  continued  until  the  mass 
becomes  dry,  and  the  latter  is  then  moistened  with  strong  acid 
and  digested  with  water,  the  bases  will  go  into  solution,  while 
the  silica  remains  insoluble  and  may  be  separated  by  filtering. 
Comparative  tests  have  shown  that  gelatinization  is  more  readily 
obtained  with  nitric  than  with  hydrochloric  acid,  although  in 
many  cases  either  will  answer.  As  most  silicates  are  insoluble 
in  acids,  a  previous  decomposition,  by  fusion  with  sodium  carbon- 
ate, is  usually  necessary  before  applying  the  test  (compare  §  4). 

To  illustrate  the  foregoing,  in  the  case  of  soluble  silicates,  take  about  2 
ivory  spoonfuls  of  finely  powdered  calamine  (ZnOH)aSi03,  or  nepheline, 
•essentially  ]S"aAlSi04,  mix  in  a  test-tube  with  about  1  cc.  of  water,  then 
add  3  cc.  of  nitric  or  hydrochloric  acid,  warm,  and  observe  that  the  mineral 
yields  a  perfectly  clear  solution.  Boil  the  solution,  and  it  will  soon  become 
thick  from  the  separation  of  gelatinous  silica.  The  gelatinous  silica  is 
insoluble  in  water  and  acids,  and,  if  thoroughly  washed  with  water  and 
dried  over  sulphuric  acid,  has  essentially  the  composition  H2Si03.  The 
reason  for  adding  the  water  at  the  beginning  of  this  experiment  is  to 
thoroughly  mix  the  mineral  with  the  acid.  If  omitted,  the  acid  when  it  first 
comes  in  contact  with  the  dry  material  will  often  form  a  layer  of  gelatinous 
silica  over  the  powder  and  prevent  a  portion  of  it  from  going  into  solution. 

2.  Separation  of  Silica  without  Gelatinization. — Some  sili- 
cates are  completely  decomposed  by  boiling  with  acids,  the  bases 
going  into  solution,  while  the  silica  is  left  in  an  insoluble  condi- 
tion, but  without  any  formation  of  a  jelly.  From  the  appearance 
of  the  test  it  is  sometimes  rather  difficult  to  tell  whether  a  mineral 
lias  been  decomposed  or  not,  but  the  separated  silica,  having  a 
low  index  of  refraction,  makes  the  liquid  in  which  it  is  suspended 
appear  translucent  and  almost  clear,  while  the  fine,  suspended 
powder  of  an  insoluble  mineral  causes  the  liquid  to  appear  white 
and  milky.  A  sure  test  is  to  filter,  and  evaporate  a  drop  of  the 
solution  on  a  piece  of  glass  or  platinum,  when,  if  a  considerable 
residue  is  left,  it  indicates  that  a  decomposition  has  taken  place, 
and  the  bases  have  gone  into  solution. 

An  experiment  to  illustrate  the  above  may  be  made  by  boiling  2  ivory 
spoonfuls  of  finely  powdered  serpentine  or  stilbite  with  5  cc.  of  hydrochloric 
acid. 


REACTIONS   OF   THE    ELEMENTS.  Silicon 

3.  Fusion  with  Sodium  Carbonate.— When  quartz,  SiO2,  or  a 
silicate  is  fused  with  sodium  carbonate,  a  sodium  silicate  is  formed. 
Moreover,  the  fused  mass  will  be  soluble  in  acids,  and,  upon  evapo- 
ration of    the  solution,  gelatinous    silica    separates,    as  in  §  1. 
Fusion  with  sodium  carbonate  is  indispensable  for  the  solution  and 
subsequent  analysis  of  insoluble  silicates  (compare  §  4). 

To  illustrate  the  foregoing  paragraph,  take  some  very  finely  powdered 
quartz,  Si02 ,  and  an  equal  volume  of  sodium  carbonate  (rather  less  sodium 
carbonate  than  more),  make  into  a  paste  with  water,  then  support  some  of 
the  mixture  on  a  small  loop  on  platinum  wire  and  heat  with  an  intense 
blowpipe  flame.  Instead  of  fusing  on  a  platinum  loop,  the  experiment  suc- 
ceeds beautifully  when  a  minute  quantity  of  the  mixture  is  heated  intensely 
on  a  clean  charcoal  surface.  If  successful,  a  transparent  bead  should  result, 
and  the  experiment  illustrates  the  process  of  glass-making.  The  sodium 
carbonate  brings  about  a  decomposition  of  the  quartz,  the  anhydride  of 
silicic  acid,  with  the  formation  of  sodium  silicate  and  evolution  of  carbon 
dioxide  gas,  the  reaction  Joeing  somewhat  as  follows:  2NaaCO,  -f-  Si02.  = 
JSTa4Si04+2C09. 

4.  Special  Treatment  for  the  Detection  of  the  Common  Ele- 
ments in  Silicates. — The  methods  to  be  described  are  for  the  detec- 
tion of  aluminium,  iron,  calcium,  and  magnesium,  which  are  very 
commonly  present  in  silicates,  but  to  devise  a  scheme  applicable  to 
all  possible  cases  would  require  the  elaborate  methods  of  qualita- 
tive chemical  analysis,  which  are  beyond  the  scope  of  the  present 
work      The  scheme  has  been  made  as  simple  as  possible,  and  the 
tests  can  be  performed  upon  a  small  quantity  of  material  and  in  a 
short  time,  but  the  beginner  will  find  it  necessary  to  follow  the 
details  quite  closely. 

If  a  silicate  is  insoluble  in  acids,  it  may  be  decomposed  readily 
by  fusion  with  sodium  carbonate  and  then  dissolved.  For  a  test, 
mix  a  scant  ivory  spoonful  of  the  finely  powdered  silicate  with  3 
parts  of  sodium  carbonate,  make  into  a  paste  with  a  drop  of  water 
and  then  take  up  a  portion  of  the  material  on  a  loop  on  platinum 
wire  and  fuse  before  the  blowpipe.  Make  two  or  three  beads,  if 
necessary,  rather  than  attempt  to  fuse  all  of  the  material  at  once. 
In  almost  all  cases  there  results  after  fusion  an  opaque  mass,  the 
presence  of  various  oxides  contained  in  the  mineral,  mixed  with 


Silicon  REACTIONS    OF   THE    ELEMENTS.  Ill 

the  sodium  silicate  and  excess  of  sodium  carbonate,  preventing  the 
formation  of  a  clear  glass  as  in  §  3.  The  several  beads,  after 
removal  from  the  platinum  wire,  are  pulverized  in  a  diamond 
mortar,  transferred  to  a  test-tube,  treated  with  about  1  cc.  of  water 
and  an  equal  volume  of  nitric  acid,  and  evaporated  to  dryness, 
being  careful  toward  the  end  of  the  operation  not  to  allow  the  tube 
to  become  very  hot.  After  cooling,  moisten  the  contents  of  the 
tube  with  about  3  cc.  of  hydrochloric  acid,  boil  for  a  few  seconds, 
so  as  to  decompose  any  basic  salts  formed  during  the  evaporation^ 
then  add  5  cc.  of  water,  heat  to  boiling,  and  remove  the  insoluble 
silica  by  filtering.  The  silica  separated  at  this  point  should  be 
white,  and  may  be  tested  as  follows  :  Wash  well  on  the  paper  with 
water,  but  do  not  add  the  washings  to  the  first  filtrate,  puncture 
the  paper,  and,  by  means  of  a  jet  of  water,  wash  the  silica  into  a 
clean  test-tube,  then  add  a  little  potassium  hydroxide  and  boil, 
when- the  silica,  if  pure,  will  go  wholly  into  solution. 

The  filtrate  from  the  silica  contains  the  bases,  with  the  iron  in 
the  ferric  condition,  owing  to  the  use  of  nitric  acid.  The  solution 
is  heated  to  boiling,  and  ammonia  is  added  in  slight  excess  to  pre- 
cipitate aluminium  and  ferric  hydroxides  (p.  42,  §  2,  and  p.  87  §  5), 
which  are  collected  on  a  filter  and  washed  with  water.  If  the  pre- 
cipitate is  light-colored,  iron  is  absent,  or  present  only  in  small 
quantity  ;  if  it  is  reddish-brown,  indicating  iron,  aluminium  may 
be  also  present,  and  must  be  specially  tested  for,  as  follows :  By 
means  of  a  knife-blade  or  spatula  scrape  off  the  precipitate  from  the 
filter,  and  with  the  aid  of  a  jet  of  watei  transfer  it  to  a  clean  test- 
tube,  or  fold  up  the  paper  with  the  precipitate,  and  drop  it  inta 
the  test-tube.  Have  about  5  cc.  of  water  present,  then  add  some 
potassium  hydroxide  (a  piece  of  stick  potash  5  mm.  long),  and 
boil,  by  which  treatment  aluminium  hydroxide  is  dissolved,  and 
may  be  separated  from  the  iron  by  filtering.  The  solution  is  made 
acid  with  hydrochloric  acid,  boiled,  and  ammonia  added  in  excess, 
when  aluminium,  if  present,  will  be  precipitated.  Whether  fer- 
rous or  ferric  iron  is  contained  in  the  mineral  must  be  determined 
by  special  tests  (p.  85,  §  4). 

The  filtrate  from  the  iron  and  aluminium  may  contain  calcium 


112  REACTIONS   OF   THE   ELEMENTS.  Silicon 

and  magnesium  (if  much  magnesium  is  present,  some  of  it  may 
have  been  precipitated  by  ammonia  along  with  the  iron  and  alumin 
ium).  It  is  heated  to  boiling,  and  a  little  ammonium  oxalate 
added  in  order  to  precipitate  the  calcium  (p.  60,  §  6).  Calcium 
oxalate  is  precipitated  in  a  very  finely  divided  condition,  and  is 
liable  to  run  through  filter-paper.  It  is  best,  therefore,  to  let  the 
precipitate  stand  for  about  ten  minutes  before  filtering,  and  then, 
if  the  filtrate  is  turbid,  to  pass  it  a  second  or  third  time  through 
the  same  filter  until  the  pores  of  the  paper  become  stopped,  and  * 
clear  filtrate  is  obtained.  To  the  filtrate,  a  little  ammonium  oxalate 
is  added  to  make  sure  of  the  complete  precipitation  of  the  calcium, 
and,  if  no  precipitate  forms,  some  sodium  phosphate  and  strong 
ammonia  are  added  to  precipitate  the  magnesium  (p.  91,  §  1).  If 
a  precipitate  does  not  form  immediately,  however,  it  must  not  be 
considered  that  magnesium  is  absent,  for,  if  only  a  small  quantity 
is  .present,  and  especially  if  the  solution  is  warm,  the  precipitate 
may  not  appear  until  after  standing  some  time  in  the  cold.  For 
alkalies,  the  tests  given  under  sodium  (p.  116,  §  1,  c)  and  potassium 
(p.  105,  §  1,  c)  are  recommended. 

5.  Test  with  the  Salt  of  Phosphorus  Bead. — Oxide  of  silicon 
dissolves  with  difficulty  in  a  salt  of  phosphorus  bead ;  therefore, 
when  some  powdered  silicate  is  fused  in  the  bead,  the  silica,  SiO2 , 
is  left  as  an  insoluble  skeleton  or  translucent  mass,  while  the  bases 
go  into  solution.     The  test  may  be  recommended  on  account  of  its 
simplicity,  but  it  is  not  delicate. 

In  order  to  test  the  above,  touch  the  phosphorus  bead  when  hot  to  any 
powdered  silicate,  so  as  to  take  up  a  quantity  which  before  heating  does  not 
quite  cover  one  half  the  surface  of  the  bead,  and  then  heat  before  the 
blowpipe,  in  the  hottest  part  of  the  flame.  As  the  bases  dissolve  in  the  hot 
glass,  the  silica  moves  about  and  collects  together,  and,  when  examined 
with  a  lens,  it  appears  as  a  translucent  mass,  usually  occupying  a  position  in 
about  the  center  of  the  bead,  and  is  quite  different  in  appearance  from 
any  undissolved  mineral.  Sometimes  it  is  better  to  heat  a  fragment  of  the 
mineral  in  the  bead,  and  after  igniting  for  some  time,  the  translucent  silica 
skeleton  may  be  seen  surrounding  a  particle  of  the  still  undecomposed 
mineral. 

6.  Decomposition  with  Borax. —  Silicates  are  quite  soluble  in 
a  borax  bead,  and  it  may  be  sometimes  found  convenient  to  sub- 


Silver  REACTIONS   OF   THE   ELEMENTS,  113 

stitute  this  treatment  for  fusion  with  sodium  carbonate  in  order 
to  decompose  a  silicate. 

Silver,  Ag. — Univalent.     Atomic  weight,  108. 

OCCURRENCE. — Some  silver  is  found  native  and  as  chloride  or 
bromide,  but  by  far  the  greater  part  of  the  metal  of  commerce  is 
obtained  from  its  compounds  with  sulphur.  A  few  of  the  most 
important  silver  minerals  are  argentite,  Ag2S ;  stromeyerite,  AgCuS; 
pyrargyrite,  3Ag2S.Sb2S3 ;  proustite,  3AgaS.AsaS, ;  stephanite, 
5Ag2S.  Sb,S3 ;  polybasite,  essentially  9Ag2S.Sb2S3 ;  cerargyrite, 
AgCl ;  and  embolite,  AgCl  with  AgBr.  Silver  is  found  in  sev- 
eral combinations  with  tellurium,  and  in  small  quantity  in  many 
sulphides  ;  as  in  galena,  sphalerite,  chalcocite,  bornite,  and  tetra- 
hedrite,  which  are  then  called  argentiferous.  Owing  to  the 
value  of  silver,  it  is  profitable  to  extract  it  from  ores  which  con- 
tain only  a  small  percentage  of  the  metal.  An  ore,  for  example, 
having  one  per  cent  of  silver  would  yield  291  troy  ounces  of  the 
metal  per  ton,  and,  under  favorable  conditions,  ores  containing 
less  than  one  tenth  of  the  above  amount  may  be  profitably  worked. 

DETECTION.— The  metal  is  usually  detected  by  reduction  to 
the  metallic  state  or  by  precipitation  as  silver  chloride. 

1.  Reduction  to  Metallic  Silver. — From  pure  silver  minerals, 
the  metal  may  be  readily  obtained  on  charcoal  by  fusion  before 
the  blowpipe  with  about  3  volumes  of  sodium  carbonate.  The 
metal  easily  fuses  to  a  globule,  and  this  is  bright  both  while  in 
the  flame  and  after  cooling,  for  the  metal  does  not  tend  to  oxidize. 
The  silver  globule  is  malleable,  can  be  flattened  by  hammering  on 
an  anvil,  and  may  be  further  tested  according  to  §  3.  When  other 
readily  reducible  metals  are  present,  the  globule  obtained  by  the 
above  treatment  will  not  be  pure  silver,  and  fusion  with  test-lead 
and  cupellation  on  bone-ash  (§  2)  may  then  be  resorted  to.  Often 
fusion  on  a  clean  charcoal  surface  in  the  oxidizing  flame  with  bo- 
rax is  sufficient  to  free  the  metal  from  impurities,  since  the  foreign 
substances  oxidize,  dissolve  in  the  borax,  and  leave  finally  a  globule 
of  pure  silver.  When  in  combination  with  only  volatile  elements 


114  REACTIONS   OF   THE   ELEMENTS.  Silver 

(sulphur,  arsenic,  antimony),  a  silver  globule  may  be  obtained  by 
heating  some  of  the  mineral  alone  on  charcoal  in  the  oxidizing 
flame.  Silver  is  volatile  to  a  slight  degree,  but  alone  on  charcoal 
it  gives  no  characteristic  coating.  When  silver  is  associated  with 
lead  and  antimony,  however,  the  coatings  which  these  latter  ele- 
ments give  on  charcoal  assume  a  reddish  to  deep  lilac  tint,  which 
serves  as  a  very  certain  indication  of  the  presence  of  silver. 

2.  Cupellation  on  Bone-ash  and  Detection  of  Small  Quantities  of 
Silver. — A  method  well  adapted  for  the  detection  of  even  very  small  quanti- 
ties of  silver  in  minerals  or  ores  is  to  mix  an  ivory  spoonful  of  the  finely  pow- 
dered material  with  an  equal  volume  each  of  borax  glass  and  test-lead, 
transfer  to  a  rather  deep,  funnel-shaped  cavity  in  a  compact  piece  of  char- 
coal, and  fuse  before  the  blowpipe  for  some  time  in  a  reducing  flame  until 
the  lead,  which  takes  up  all  the  silver,  has  united  into  one  globule,  while 
the  impurities  dissolve  in  the  borax.  Later  an  oxidizing  flame  may  be  used 
in  order  to  form  lead  oxide,  which  dissolves  in  the  borax  and  assists  in  taking 
up  the  impurities.  After  cooling,  the  lead  is  removed  from  the  charcoal,  and 
freed  from  adhering  slag  by  hammering  on  an  anvil.  A  cupel  is  next  pre- 
pared by  filling  a  cavity  on  charcoal  with  bone-ash,  and  pressing  the  latter 
down  firmly  by  means  of  an  agate  pestle  or  other  smooth  rounded  surface, 
such  as  the  back  of  the  metal  scoop  (Fig.  22),  so  as  to  form  a  shallow  de- 
pression about  15  mm.  in. diameter.  Loose  particles  of  bone-ash  are  removed 
by  inverting  and  gently  tapping  the  charcoal,  and  the  cupel  is  heated  in- 
tensely before  the  blowpipe  in  order  to  expel  moisture.  The  lead  button  is 
then  placed  carefully  upon  the  cupel,  so  as  not  to  disturb  the  surface  of  the 
bone-ash,  and  fused  before  the  blowpipe,  first  in  the  reducing  flame  until 
a  bright  metallic  surface  is  obtained,  and  then  in  a  small  oxidizing  flame 
(Fig.  41).  It  is  necessary  to  heat  in  the  oxidizing  flame  for  several  minutes 
in  order  to  oxidize  the  lead,  during  which  time  the  surface  of  the  button 
shows  a  play  of  rainbow  colors,  due  to  a  thin  film  of  lead  oxide,  which  con- 
stantly flows  to  the  sides,  and  is  absorbed  by  the  bone-ash.  Finally,  when 
the  last  of  the  lead  is  oxidized,  the  play  of  color  ceases,  the  globule  is  said 
to  "  bliclc"  and  the  operation  is  completed.  Frequently  the  amount  of  lead 
oxide  formed  is  so  great  that  it  cannot  all  be  absorbed  by  one  cupel.  The 
button  then  becomes  surrounded  by,  and  seems  to  float  upon,  the  fused  lead 
oxide,  and  when  this  happens,  it  is  best  to  interrupt  the  operation  and  oxidize 
the  last  of  the  lead  upon  a  fresh  cupel. 

Considerable  practice  is  needed  in  order  to  make  the  silver  assay  easily 
and  quickly,  but  when  the  necessary  skill  has  been  acquired,  the  operation 
may  be  performed  in  less  than  fifteen  minutes,  and  by  assaying  samples  of 
known  value  and  saving  the  silver  beads  for  comparison,  one  can  soon  learn 


Sodium  REACTIONS   OF   THE   ELEMENTS.  115 

to  judge  of  the  relative  values  of  ores.  By  starting  with  weighed  quantities 
of  material,  and  especially  by  making  use  of  the  special  apparatus  men. 
tioned  in  Plattner's  elaborate  treatise,*  very  good  quantitative  determina- 
tions of  silver  may  be  made  by  means  of  the  blowpipe  assay. 

3.  Precipitation  as  Silver  Chloride.— Silver  chloride,  AgCl,  is 
very  insoluble  in  water  and  dilute  nitric  acid.  A  white  precipitate 
of  silver  chloride  will  therefore  form  if  silver  is  dissolved  in  di- 
lute nitric  acid  (1HNO, :  2H2O)  and  a  few  drops  of  hydrochloric  acid 
are  added  to  the  solution.  If  the  quantity  of  the  precipitiate  is 
small  it  appears  as  a  turbidity,  while  if  ic  is  considerable  it  col- 
lects as  a  curdy  mass.  It  darkens  on  exposure  to  light  and  is 
readily  soluble  in  ammonia.  A  globule  of  silver  from  one  of  the 
foregoing  experiments  may  be  tested  in  this  way.  It  is  also  often 
convenient  to  test  for  silver  by  dissolving  a  mineral  in  hot,  concen- 
trated, nitric  acid,  and,  after  dilution,  and  filtering  if  necessary,  to 
precipitate  the  silver  with  hydrochloric  acid.  The  precipitate,  if 
collected  on  a  filter,  may  be  tested  according  to  §  1. 

Sodium,  Na. — Univalent.     Atomic  weight,  23. 

OCCUIIRENCE.  —  Sodium  is  a  very  abundant  element,  and  al- 
though its  simple  salts  are  all  soluble  in  water  and  are  not  ordi- 
narily found  as  minerals  in  wet  regions,  they  often  accumulate  in 
desert  or  dry  places,  and  form  deposits  of  great  commercial  value. 
The  most  important  compound  is  halite,  NaCl,  which  is  found  both 
as  rock  salt  and  in  solution  in  the  water  of  the  oceans.  Double 
salts  containing  sodium,  which  are  insoluble  in  water  and  often 
also  in  acids  (for  example,  albite,  K"aAlSi308),  are  very  common, 
especially  in  the  group  of  silicates. 

DETECTION. — Sodium  is  usually  detected  by  means  of  the  flame 
coloration  and  alkaline  reaction. 

1.  Flame  Test.  —Volatile  sodium  compounds  color  the  flame 
yellow,  and  the  test  is  exceedingly  delicate.  The  color  is  monochro- 
matic, and  therefore  shows  only  a  single  band  in  the  spectroscope. 
The  flame  color  cannot  be  seen  through  moderately  dark  blue  glass, 
as  the  yellow  rays  are  wholly  absorbed  (see  Potassium,  p.  105,  §  1). 
*  Probirkunst  init  dem  Lothrohre.  American  translation  by  Cornwall. 


116  REACTIONS   OF  THE   ELEMENTS.  Sodium 

a.  To  illustrate  the  above,  fuse  in  the  forceps  some  halite  or  cryolite 
before  the  blowpipe,  or,  still  better,  fuse  some  of  the  material  into  a  loop  on 
platinum  wire  and  introduce  it  into  a  Bunsen-burner  flame  at  about  the 
point  r,  Fig.  35,  p.  32. 

b.  To  illustrate  the  great  delicacy  of  the  reaction,  heat  a  platinum  wire 
until  it  gives  no  color  to  the  flame,  then  draw  it  through  the  fingers,  heat 
again,  and  observe  the  yellow  color  which  results  from  the  minute  trace  of 
sodium  derived  from  contact  with  the  fingers.     The  flame  test  is  so  exceed- 
ingly delicate  that  a  great  deal  of  judgment  must  be  exercised  in  making 
use  of  it.     A  mineral  should  be  regarded  as  containing  sodium  only  when  it 
gives  an  intense  and  prolonged  yellow  coloration,  as  in  the  previous  test. 

c.  Silicates  from  which  sodium  is  not  readily  volatilized  may  be  fused 
with  gypsum,  as  directed  under  potassium  (p.  105,  §  1,  c). 

2.  Alkaline  Reaction. — With  the  exception  of  the  silicates, 
phosphates,  borates,  and  the  salts  of  a  few  rare  acids,  sodium  com- 
pounds become  alkaline  upon  ignition  before  the  blowpipe.  A 
similar  reaction  is  obtained  from  other  minerals  containing  the  al- 
kalies and  alkaline  earths. 

«.  Make  a  loop  about  3  mm.  in  diameter  on  platinum  wire,  fuse  some 
halite  in  it,  and  continue  to  heat  for  some  time,  but  not  long  enough  to 
volatilize  all  the  material.  In  order  to  test  the  alkaline  reaction,  bring 
the  fused  mass  in  contact  with  a  piece  of  moistened  turmeric-paper  on  a 
clean  glazed  surface.  In  this  experiment,  water  (one  of  the  products  of 
combustion)  acting  at  a  high  temperature  brings  about  a  partial  decomposi- 
tion of  the  material,  as  follows:  NaCl  +  H20  =  NaOH  +  HC1. 

b.  If  a  fragment  of  cryolite,  Na3AlF6,is  fused  in  a  loop  on  platinum 
wire  and  heated  before  the  blowpipe,  the  hydrofluoric  acid  which  is  driven 
off  may  be  readily  detected  by  its  pungent  odor,  or  by  the  reddening  of  a 
moistened  blue  litmus-paper  held  at  a  little  distance  beyond  the  flame,  while 
the  residue  will  impart  an  alkaline  reaction  to  moistened  turmeric-paper. 

Strontium,  Sr. — Bivalent.     Atomic  weight,  87.5. 

t 
OCCURRENCE. — Strontium  is  found  quite  abundantly  as  celes- 

tite,  SrSO4 ,  and  strontianite,  SrCO3 ,  but  other  combinations  are 
rare  (brewsterite). 

DETECTION. — Strontium  is  usually  detected  by  the  flame  color- 
ation, alkaline  reaction  after  heating,  and  by  precipitation  as  sul- 
phate. 

1.  Flame  Test. — Strontium  compounds  when  heated  before  the 
blowpipe  impart  a  crimson  color  to  the  flame,  and  this  may  be  ob- 


Strontium  REACTIONS   OF   THE   ELEMENTS.  117 

tained  by  igniting  fragments  held  in  the  platinum-pointed  forceps, 
or  often  still  better  by  taking  up  some  of  the  powdered  mineral  on 
'  platinum  wire,  as  directed  on  p.  35,  and  heating  before  the  blow- 
pipe or  in  the  Bunsen-burner  flame.  Often  the  coloration  can  be 
made  more  intense  by  moistening  the  material  with  hydrochloric 
acid.  TKe  crimson  flame  must  not  be  mistaken  for  lithium,  or,  in 
case  hydrochloric  acid  is  used,  for  the  yellowish-red  of  calcium 
(p.  59,  §  2) ,  which,  however,  is  not  as  persistent  on  prolonged  heat- 
ing as  the  crimson  of  strontium.  A  spectroscope  can  be  used  to 
advantage. 

2.  Alkaline  Reaction. — Strontram  compounds  become  alkaline 
upon  ignition  before  the  blowpipe,  with  the  exception  of  the  sili- 
cates and  phosphates  (compare  Calcium,  p.  58,  §  1).  A  similar  re- 
action is  obtained  from  other  minerals  containing  the  alkalies  and 
alkaline  earths.  There  are  no  lithium  minerals  known  which  yield 
an  alkaline  reaction  after  ignition,  and  therefore  a  crimson  flame 
in  connection  with  alkaline  reaction  is  an  almost  certain  proof  of  the 
presence  of  strontium. 

8.  Precipitation  as  Strontium  Sulphate. — Strontium  sulphate, 
SrSO4 ,  is  very  insoluble  in  water  and  dilute  acids,  and  may  be 
precipitated  by  adding  a  few  drops  of  dilute  sulphuric  acid  to 
solutions,  provided  the  latter  are  not  very  dilute  and  do  not  con- 
tain too  much  acid.  The  test  will  be  found  convenient  in  distin- 
guishing strontium  from  lithium  and  calcium,  and  for  the  detec- 
tion of  strontium  in  silicates  and  phosphates  which  do  not  yield 
a  flame  coloration  or  alkaline  reaction  (compare  Barium,  p.  53, 
§  3,  b). 

Dissolve  an  ivory  spoonful  of  strontianite  in  3  cc.  of  warm  hydrochloric 
acid,  divide  the  solution  into  2  parts,  dilute  one  with  about  5,  and  the  other 
witli  15  cc.  of  water,  and  add  a  few  drops  of  dilute  sulphuric  acid  to  each. 
In  the  more  concentrated  solution,  the  precipitate  forms  almost  immedi- 
ately, but  in  the  other,  only  after  standing  for  several  minutes,  while  an  ex- 
periment made  in  exactly  the  same  manner  with  calcite,  CaC03,  would  not 
yield  a  precipitate  of  CaS04  in  either  solution  (see  p.  59,  §  3) .  In  order 
to  precipitate  strontium  completely  as  sulphate,  it  is  necessary  to  add  an 
equal  volume  of  alcohol  to  the  liquid. 


118  KEACTIONS   OF   THE   ELEMENTS.  Sulphur 

4.  Specific  Gravity.  —  Strontium  compounds  are  heavy,  and 
their  specific  gravities  lie  between  those  of  the  corresponding  cal- 
cium and  barium  salts,  as  the  following  examples  show  : 

Specific  Gravity.  Specific  Gravity. 

Aragonite,  CaCG,          2.95  Anhydrite,  CaS04,     2.98 

Strontianite,  SrCO,,      3.70  Celestite,  SrS04,         3.96 

Witherite,  BaC03,         4.35  Barite,  BuS04,  4.48 

Sulphur,  S.  —  Bivalent  and  sexivalent.     Atomic  weight,  32. 

OCCURRENCE.  —  In  addition  to  being  found  native,  sulphur  also 
occurs  in  two  very  important  classes  of  compounds,  the  sulphides 
and  sulphates.  The  sulphides  may  be  generally  regarded  as  salts  of 
the  weak  acid,  hydrogen  sulphide,  HaS,  and  the  common  ores  of 
many  of  the  valuable  metals  are  of  this  class  ;  as  argentite,  Ag2S  ; 
galena,  PbS;  sphalerite,  ZnS;  cinnabar,  HgS,  etc.  The  sulphates  are 
salts  of  sulphuric  acid,  H3SO4  ,  and  the  metals  calcium,  strontium, 
barium,  and  lead,  form  insoluble  sulphates,  which  occur  abundantly 
in  nature.  Soluble  sulphates,  especially  those  of  the  alkali  metals, 
may  accumulate  in  arid  regions,  and  a  number  of  double  salts  and 
basic  sulphates  are  known.  Sulphur  is  found  rarely  in  combina- 
tion with  a  silicate  ;  as  in  helvite,  Mna(MnaS)Be3(Si04)3  and  noseite, 


SULPHIDES. 

DETECTION.  —  Sulphides  may  be  most  conveniently  detected  by 
an  oxidizing  process,  such  as  roasting  in  the  open  tube  or  on  char- 
coal. 

1.  Oxidation  or  Roasting  in  the  Open  Tube.  —  An  exceedingly 
delicate  test  for  a  sulphide  is  to  heat  some  of  the  finely  powdered 
mineral  in  an  open  tube,  when  sulphur  dioxide,  SO,,  and  usually 
an  oxide  of  the  metal  are  formed.  Sulphur  dioxide,  the  anhydride 
of  sulphurous  acid,  is  a  colorless  gas,  which  may  be  readily  detected 
by  its  sharp,  pungent  odor  and  the  acid  reaction  which  it  imparts 
to  a  piece  of  moistened  litmus-paper  placed  at  the  end  of  the  tube. 

According  to  the  directions  given  on  p.  19,  heat  about  -fa  of  an  ivory 
spoonful  of  finely  powdered  galena  in  an  open  tube  until  the  odor  of  sulphur 
dioxide  (burning  sulphur)  ceases,  and  the  dark  lead  sulphide  has  changed 


Sulphur  REACTIONS   OF   THE   ELEMENTS.  119 

wholly  to  light-colored  lead  oxide.  The  reaction  is  essentially  as  follows  : 
PbS  -f-  30  =  PbO  +  S0a.  Lead  oxide  and  sulphur  dioxide  combine  to  form  a 
rather  volatile  product,  and  a  trace  of  this  will  usually  be  found  as  a  white  sub- 
limate a  little  above  the  lead  oxide.  The  open-tube  test  is  so  delicate  that 
when  a  minute  particle  of  a  sulphide  is  used,  an  acid  reaction  will  be  imparted 
to  test-paper  and  usually  even  the  odor  of  S02  will  not  escape  detection. 

When  sulphides  of  iron,  copper,  and  some  other  metals  are  roasted  in 
the  open  tube,  the  oxides  of  the  metals  which  are  formed  during  the  opera- 
tion act  as  oxidizing  agents,  and  convert  some  S02  to  S03,  the  anhydride  of 
sulphuric  acid :  Fe303  -f  S03  =  2FeO  +  S03.  The  formation  of  S03  is 
indicated  by  white  fumes  passing  up  the  tube,  and  some  of  the  S03  derives 
sufficient  moisture  from  the  atmosphere  to  form  a  little  HaS04  which  con- 
denses as  a  liquid  in  the  tube. 

2.  Oxidation  or  JZoasting  on  Charcoal. — An  excellent  method 
for  detecting  sulphur,  but  not  so  delicate  as  the  one  just  given,  is  to 
roast  the  finely  powdered  sulphide  on  charcoal  according  to  the  di- 
rections given  on  p.  39,  and  observe  the  odor  of  S0a.     This  test  is 
especially  recommended  for  sulphides  which  contain  a  great  deal 
of  sulphur. 

3.  Roasting  in  the  Platinum  Forceps. — Some  sulphides  oxidize 
so  readily  that,  when  held  in  the  forceps  and  heated  before  the 
blowpipe,  they  take  fire  and  continue  to  burn  for  some  time,  giving 
a  strong  odor  of  S0a.    Pyrite,  FeS3 ,  and  chalcopyrite,  CuFeS2,can 
be  tested  in  this  way. 

4.  Heating  in  a  Closed  Tube. — Many  sulphides  suffer  no  de- 
composition when  heated  in  a  closed  tube,  while  others  part  with 
a  portion  of  their  sulphur,  which  condenses  on  the  walls  of  the 
tube  as  a  fused  sublimate,  having  a  dark  amber  color  when  hot, 
changing  to  pale  yellow  and  becoming  crystalline  when  cold.     A 
sulphide  of  the  metal  always  remains  in  the  tube,  and  the  test, 
although  admirable   for  some  sulphides,  is  not  applicable  in  all 
cases.      Owing  to  the  air  in  the  tube,  there  will  always  be  some 
oxidation  and  formation  of  a  little  SO, ,  but  necessarily  this  must 
be  trifling  in  amount,  since  there  is  no  free  circulation  of  the  air 
and  only  about  one  fifth  of  it  is  oxygen. 

Excellent  experiments  for  illustrating  the  behavior  of  different  sulphides 
may  be  made  by  heating  fragments  of  pyrite,  FeS, ,  and  galena,  PbS,  in 


120  REACTIONS   OF  THE    ELEMENTS.  Sulphur 

separate  tubes.  The  first  gives  an  abundant  sublimate  of  sulphur,  but 
sulphide  of  iron,  FeS,  is  left  in  the  tube,  as  may  be  proved  by  removing 
some  of  the  material  and  roasting  on  charcoal  or  in  the  open  tube.  The 
galena,  on  the  other  hand,  gives  no  sublimate,  as  there  is  no  excess  of 
sulphur  above  the  normal  sulphide,  PbS. 

5.  Test  on  Silver  after  Fusion  with  Sodium  Carbonate.— When 
a  powdered  sulphide  is  mixed  with  about  3  parts  of  sodium  carbon- 
ate  and  fused  before  the  blowpipe  on  charcoal,  sodium  sulphide  will 
be  formed,  owing  to  the  strong  chemical  affinity  of  sodium  for  sul- 
phur.    If  some  of  the  fused  mass  or  of  the  charcoal  into  which  it 
has  been  absorbed  is  placed  with  a  drop  of  water  on  a  clean  silver 
surface,  a  black  stain  of  silver  sulphide  will  be  formed.     The  test 
is  so  delicate  that,  if  sodium  carbonate  is  heated  alone  on  charcoal 
before  the  blowpipe  for  a  long  time  with  a  gas  flame,  and  then 
placed  upon  moistened  silver,  a  slight  discoloration  may  result 
from  the  traces  of  sulphur  contained  in  the  gas  and  charcoal,  but 
it  is  not  necessary  to  mistake  this  slight  discoloration  for  the  strong 
reaction  given  by  sulphides.     If  selenium  and  tellurium  are  pres- 
ent, the  test  cannot  be  relied  upon. 

6.  Oxidation  and  Solution  by  Means  of  Nitric  Acid. — Nitric 
acid,  owing  to  its  strong  oxidizing  action,  serves  as  the  best  solvent 
for  sulphides.    If  hot,  concentrated  acid  is  used,  there  are  two  pro- 
cesses to  be  considered,  which  go  on  simultaneously  ;  (1)  oxidation, 
and  (2)  solution  of  the  products  of  oxidation.     The  final  products 
may  be  generally  regarded  as  sulphuric  acid  and  nitrates  of  the 
metals.     For  example,  pyrite,  FeS, ,  is  oxidized  to  sulphuric  an- 
hydride, SO, ,  and  ferric  oxide,  Fe,O3 ,  and  the  first  of  these  com- 
bines with  water  to  form  sulphuric  acid,  H2SO4 ,  while  the  sec- 
ond dissolves  in  the  nitric  acid  to  form  ferric  nitrate,  Fe(NOs)8. 
Since  the  metals  oxidize  more  readily  than  sulphur,  it  frequently 
happens  that  a  portion  of  the  latter  separates  in  a  free  state  as 
a  spongy  mass.    This  separated  sulphur  oxidizes  very  slowly,  and  is 
yellow  if  pure,  but  is  frequently  black,  owing  to  some  undecom- 
posed  sulphide,  which  is  held  mechanically  in  the  sulphur  and  is 
thus  protected  from  the  action  of  the  acid.     When  a  sulphide  is 
decomposed  with  concentrated  nitric  acid,  no  volatile  sulphur  com- 


REACTIONS   OF   THE    ELEMENTS.  121 

pounds  are  formed,  but  all  the  sulphur  remains  either  oxidized  to 
sulphuric  acid  or  partly  separated  in  the  free  state. 

While  oxidation  is  going  on,  the  nitric  acid  must  suffer  decon> 
position,  but  this  may  take  place  in  different  ways ;  for  example, 
2HNO,=  O  +  2NO,+  H,O,  or  2HNO3  =  30  +2NO  +  H2O.  In  either 
case,  red  vapors  of  NO2  will  be  visible,  for,  provided  the  decomposi- 
tion takes  place  according  to  the  last  equations,  the  colorless  gas, 
NO,  takes  on  oxygen  as  soon  as  it  comes  in  contact  with  the  air,  and 
changes  to  NOa.  Since  in  the  solution  of  sulphides  in  nitric  acid 
there  is  no  certainty  regarding  the  exact  manner  in  which  the  acid 
will  break  up  in  order  to  bring  about  the  oxidation,  it  is  scarcely- 
practical  to  express  the  reaction  by  means  of  equations,  but  when 
red  fumes  of  NO,  gas  are  abundantly  given  off,  it  is  a  sure  indica- 
cation  that  oxidation  is  going  on. 

a.  In  order  to  illustrate  this,  treat  about  \  ivory  spoonful  of  powdered 
pyrite  in  a  dry  test-tube  with  3  cc.  of  concentrated  nitric  acid,  and  boil 
until  the  evolution  of  red  fumes  ceases.    The  red  fumes  indicate  that  an  oxi- 
dation is  going  on,  and,  if  the  experiment  is  successful,  the  mineral  should 
be  completely  dissolved.    Dilute  the  solution  with  10  cc.  of  water,  mix  thor- 
oughly, and  test  the  greater  part  of  it  in  a  separate  test-tube  with  a  little  ba- 
rium chloride,  when  a  white  precipitate  of  barium  sulphate  will  be  thrown 
down  (p.  122,  §  1),  indicating  that  sulphuric  acid  was  formed.     Dilute  the 
remainder  of  the  solution  still  further  with  water,  divide  into  2  portions, 
and  test  for  ferric  and  ferrous  iron  according  to  p.  85,  §  4.     By  this  means 
it  may  be  proved  that  the  metal,  as  well  as  the  sulphur,  has  been  converted 
into  the  higher  state  of  oxidation. 

b.  To  illustrate  the  separation  of  free  sulphur,  and  how  this  is  dependent 
upon  the  character  of  the  minerals,  decompose  equal  portions   of  pyrite, 
FeS2  (53.4$  S),  and  .pyrrhotite,   FenS19  (38.4$   S),  in  separate  test-tubes 
with  nitric  acid,  and  make  the  conditions  of  the  experiments  as  nearly  alike 
as  possible.     Observe  that  the  pyrrhotite  with  the  least  sulphur  is  the  most 
difficult  to  dissolve  completely,  and  that  by  its  decomposition  sulphur  is 
separated,  while  the   pyrite  with  the  most  sulphur  dissolves  completely. 
A  possible  explanation  of  this  is  that  pyrrhotite,  which  is  easily  soluble  in 
non-oxidizing  acids  (hydrochloric,  for  example),  with  evolution  of  HSS,  is  at 
first  decomposed  by  the  nitric  acid,  giving  HaS,  which  is  instantly  oxidized 
to  H2O  -f-  S;  while  pyrite,  which  is  insoluble  in  non-oxidizing  acids,  is  oxi- 
dized by  the  concentrated  acid  without  any  intermediate  formation  of  HaS. 

7.  Solution  in  Hydrochloric  Acid. — Most  sulphides  are  either 
insoluble  or  difficultly  soluble  in  hydrochloric  acid,  but  those  which 


122  REACTIONS   OF   THE   ELEMENTS.  Sulphur 

dissolve  always  give  hydrogen  sulphide  gas,  H2S.  The  reaction  is 
usually  a  simple  one.  FeS  +  2HC1  =  FeCl2  +  HaS.  Hydrogen  sul- 
phide is  readily  recognized  by  its  offensive  odor. 

Treat  some  finely  powdered  pyrrhotite,  FenSlt  (almost  FeS),  in  a  test- 
tube  with  3  cc.  of  hydrochloric  acid,  and  observe  that  a  gas  is  evolved  which 
has  a  disagreeable  odor. 

SULPHATES. 

DETECTION. — Either  the  barium  chloride  test,  or  the  one  on  sil- 
ver after  a  sulphide  has  been  formed  by  reduction,  may  be  used 
for  the  detection  of  sulphates.  The  oxidation  and  roasting  proc- 
esses used  for  the  detection  of  sulphur  in  sulphides  cannot  be 
applied  to  sulphates,  as  they  are  already  oxidized. 

1.  Test  with  Barium  Chloride. — If  barium  chloride  is  added  to 
a  dilute  hydrochloric  acid  solution  of  a  sulphate,  a  white  precip- 
itate of  barium  sulphate,  BaSO4,  will  form,  which  is  almost  abso- 
lutely insoluble  in  water  and  dilute  acids,  and  serves  therefore  as 
a  very  delicate  test  for  sulphates. 

If  the  sulphate  proves  to  be  an  insoluble  one,  test  according  to 
§  2,  or  fuse  some  of  it  in  a  platinum  spoon  with  6  parts  of  sodium 
carbonate,  soak  out  the  fusion  with  water,  filter,  make  the  filtrate 
slightly  acid  with  hydrochloric  acid,  boil,  and  then  test  with 
barium  chloride. 

Illustrate  the  foregoing  test  by  dissolving  -J  ivory  spoonful  of  gypsum, 
CaS04.2H20,  in  warm,  dilute  hydrochloric  acid,  and  test  the  solution  with 
a  little  barium  chloride. 

It  is  always  best  to  dilute  the  acids  before  testing  for  a  sulphate,  for  if 
barium  chloride  is  added  to  concentrated  hydrochloric  or  nitric  acid,  barium 
chloride  or  nitrate,  both  of  which  are  insoluble  in  concentrated  acids, 
might  be  thrown  down,  and  mistaken  for  barium  sulphate.  They  differ 
from  the  latter,  however,  in  that  they  dissolve  readily  upon  addition  of 
water. 

2.  Test  on  Silver  after  Reduction  to  Sulphide. — If  a  powdered 
sulphate,  mixed  with  an  equal  volume  of  charcoal  powder  and  2  of 
sodium  carbonate,  is  made  into  a  paste  with  water  and  fused  on 


Tantalum  REACTIONS   OF   THE   ELEMENTS.  123 

platinum  wire  before  the  blowpipe  until  effervescence  ceases,  the 
sulphate  will  undergo  decomposition  and  reduction,  and  sodium 
sulphide,  ]S"auS,  will  be  formed.  That  reduction  has  taken  place 
may  be  told  by  removing  the  bead  from  the  wire,  crushing  it,  and 
placing  the  material  with  a  drop  of  water  on  a  clean  silver  surface. 
Sodium  sulphide  will  thus  react  with  the  silver  and  make  a  black 
stain  of  silver  sulphide,  as  follows :  E"a2S  +  2Ag  +  H2O  +  O  = 
Ag2S  +  2NaOH.  The  test  is  exceedingly  delicate  (see  p.  120,  §  5), 
and,  although  it  proves  the  presence  of  sulphur  in  a  compound,  it 
is  not  necessarily  a  test  for  a  sulphate,  unless  it  has  been  proved 
by  a  previous  oxidizing  experiment  or  by  other  means  that  the 
mineral  is  not  a  sulphide. 

As  an  experiment,  test  barite,  BaS04 ,  as  directed  above.  The  reaction 
which  goes  on  during  fusion  is  as  follows:  BaS04  -f-  NaaC09  -j-  2C  =  Na2S 
-f-  BaC03  -f-  2C02.  Besides  testing  on  silver,  take  some  of  the  crushed  prod- 
uct, resulting  from  fusion  with  sodium  carbonate  and  charcoal,  and  digest 
it  in  a  test-tube  with  a  few  drops  of  water,  then  add  a  few  drops  of  hydro- 
chloric acid,  and  observe  the  odor  of  the  escaping  hydrogen  sulphide  gas, 
which  will  serve  as  a  certain  proof  that  the  sulphate  has  been  reduced  to  a 
sulphide. 

3.  Closed- Tube  Reactions. — The  common  sulphates,  those  of 
the  alkalies,  alkali  earths,  and  lead,  suffer  no  decomposition  when 
heated  in  a  closed  tube,  while  sulphates  of  the  less  basic  elements, 
such  as  aluminium,  iron,  and  copper,  are  more  or  less  decomposed, 
yielding  sulphuric  anhydride,  SO3 ,  or  sulphurous  anhydride,  SO2 , 
or  both.  As  water  of  crystallization  is  usually  present  in  the 
latter  compounds,  it  is  also  driven  off  and  is  made  strongly  acid 
by  the  oxides  of  sulphur  (compare  p.  82,  §  2). 

Tantalum,  Ta.— Pentavalent.     Atomic  weight,  182.6. 

OCCURRENCE. — Tantalum  is  associated  with  niobium  in  the  group  of 
minerals  known  as  the  tantalates  and  niobates  (see  Niobium,  p.  98). 

DETECTION.— There  are  no  simple  tests  for  the  detection  of  tantalum,  but 
if  niobium  is  found  in  any  compound,  it  is  almost  certain  that  tantalum  is 
also  present.  Tantalates  are  characterized  by  high  specific  gravities, 
greater  than  those  of  the  corresponding  niobium  compounds. 

In  order  to  make  a  definite  test  for  tantalum,  separate  the  mixed  tantalic 
and  niobic  oxides  by  fusion  with  potassium  bisulphate,  and  treatment  as 


124  REACTIONS   OF   THE   ELEMENTS.  Tellurtum 

directed  on  p.  99,  §  2.  Treat  the  oxides  in  a  platinum  dish  with  a  little  pure 
hydrofluoric  acid,  filter  if  necessary,  and  add  a  little  potassium  fluoride. 
Evaporate  the  solution  in  a  water-bath  nearly,  but  not  quite,  to  dryness,  dis- 
solve the  residue  in  the  smallest  possible  quantity  of  boiling  water,  and  al- 
low the  solution  to  become  cold,  when,  if  tantalum  is  present,  a  very  char- 
acteristic double  salt,  K2TaF,,  crystallizes  out  in  fine  needles.  The  crystals, 
if  collected  on  a  filter-paper  and  dried,  have  the  appearance  of  wool.  It  is 
necessary  that  the  hydrofluoric  acid  should  be  free  from  hydrofluosilicic  acid 
(alone  it  should  give  no  precipitate  with  potassium  fluoride),  and  platinum 
or  silver  vessels  must  be  used. 

Tellurium,  Te. — Usually  bivalent  in  minerals.  Atomic  weight, 
125. 

OCCURRENCE. — Tellurium  is  found  as  the  native  element,  but  more 
often  it  is  combined  with  the  metals  in  tellurides,  and  it  occurs  rarely  as 
tellurous  oxide  and  salts  of  tellurous  and  telluric  acids.  The  tellurides  are 
analogous  to  the  sulphides,  and  some  of  the  more  important  ones  are  tetrad- 
ymite,  Bi,Tes;  hessite,  AgaTe;  altaite,  PbTe;  sylvanite,  (Au,Ag)Te2;  and 
calaverite,  AuTea.  Tellurium  is  the  only  element  with  which  gold  has 
been  found  in  minerals,  in  chemical  combination. 

DETECTION. — A  very  delicate  test  for  tellurium  or  tellurides  may  be 
made  by  heating  a  little  of  the  finely  powdered  mineral  in  a  test-tube  with 
about  5  cc.  of  concentrated  sulphuric  acid,  when  the  latter  assumes  a  beauti- 
ful reddish-violet  color.  After  cooling,  addition  of  water  will  cause  the 
color  to  disappear,  and  a  grayish-black  precipitate  of  tellurium. will  be  thrown 
down. 

Another  test,  applicable  to  all  compounds  containing  tellurium,  is  to  heat 
a  mixture  of  the  finely  powdered  substance  with  sodium  carbonate  and  a 
little  charcoal  dust,  in  a  rather  large  closed  glass  tube,  by  which  means  so- 
dium telluride  is  formed,  and  after  cooling  and  addition  of  water,  the  solu- 
tion will  assume  a  reddish-violet  color.  If  a  few  drops  of  the  solution  aro 
transferred  to  a  porcelain  plate  or  watch-glass  by  means  of  a  pipette,  the 
color  soons  disappears,  and  a  gray  precipitate  of  tellurium  forms,  owing  to 
the  oxidizing  action  of  the  air.  The  color  disappears  still  more  quickly  if 
air  is  blown  through  some  of  the  solution. 

By  heating  in  the  open  tube,  tellurium  and  the  tellurides  are  oxidized, 
and  yield  TeO,,  which  passes  up  the  tube  as  a  white  smoke,  but  mostly  con- 
denses near  the  heated  part  as  a  white  sublimate.  On  heating  the  latter,  it 
volatilizes  very  slowly,  and  fuses  into  globules,  which  are  yellow  when  hot, 
and  white  or  colorless  when  cold. 

Heated  in  the  closed  tube,  tellurium  volatilizes  and  condenses  on  the  hot 
as  fused  globules  having  a  metallic  luster.  Accompanying  the  tellu- 


Tin  REACTIONS   OF   THE   ELEMENTS.  125 

rium  are  white  or  colorless  globules  of  the  oxide,  TeOa,  formed  from  the 
oxidation,  due  to  the  air  in  the  tube. 

Heated  before  the  blowpipe  on  charcoal,  tellurium  is  volatilized,  and  con- 
denses near  the  heated  part  as  a  white  sublimate  of  Te02,  somewhat  resem- 
bling antimony  oxide.  Some  tellurium  may  escape  oxidation,  and  condense 
as  a  slight  brownish  coating  distant  from  the  assay.  The  sublimates  volatil- 
ize when  heated  before  the  blowpipe  and  impart  a  pale  greenish  color  to 
the  reducing  flame. 

Thallium,  Tl.— Univalent  and  trivalent.     Atomic  weight,  203.6. 

OCCURRENCE. — Thallium  is  a  very  rare  element,  and  thus  far  only  two 
minerals  containing  it  in  considerable  quantity  have  been  observed,  crookes- 
ite,  (Cu,Tl,Ag),Se,  and  lorandite,  TlAsSa,  both  of  which  are  exceedingly 
rare. 

DETECTION. — Thallium  and  its  salts  are  quite  volatile  when  heated  be- 
fore the  blowpipe,  and  impart  an  intense  green  color  to  the  flame.  When 
the  thallium  flame  is  examined  with  the  spectroscope,  it  shows  only  one 
bright  green  band.  Heated  before  the  blowpipe  on  charcoal  in  the  reducing 
flame,  thallium  compounds  yield  a  slight  white  coating  of  thallium  oxide. 
Heated  on  charcoal  in  the  oxidizing  flame,  with  potassium  iodide  and 
sulphur,  a  yellowish-green  coating,  resembling  lead  iodide,  is  obtained,  but 
this  may  be  readily  distinguished  from  the  latter  by  the  flame  coloration. 

Thorium,  Th.—  Tetravalent.     Atomic  weight,  233. 
The  reactions  for  this  rare  element  are  given  under  Cerium. 
Tin,  Sn. — Tetravalent  in  minerals.     Atomic  weight,  119. 

OCCURRENCE. — Tin  is  found  chiefly  as  the  oxide  cassiterite, 
SnO2.  Its  combinations  with  sulphur  and  sulphides  of  the 
metals,  the  sulpJiostannates  (stannite,  Cu,FeSnS4 ,  and  canfieldite, 
Ag8SnS6),  are  rare.  Nordenskioldine  is,  perhaps,  a  basic  stannate, 
Ca(BO)2Sn04.  Traces  of  tin  are  found  in  many  columbates  and 
tantalates. 

DETECTION. — Tin  is  usually  detected  by  the  formation  of  metal- 
lic globules  by  reduction  on  charcoal. 

1.  Reduction  on  Char  coal.  —  If  i  ivory  spoonful  of  finely  pow- 
dered tin  oxide  is  mixed  with  an  equal  volume  of  powdered  char- 
coal and  2  of  sodium  carbonate,  made  into  a  paste  with  water,  and 
then  heated  on  charcoal  in  the  reducing  flame,  the  tin  will  be  read- 


126  REACTIONS  OF  THE   ELEMENTS.  Tin 

ily  reduced,  and  collect  into  globules,  which  are  bright  when  cov- 
ered with  the  reducing  flame,  but  become  coated  with  a  film  of  ox- 
ide on  exposure  to  the  air.  If  heated  intensely  before  the  blow- 
pipe, and  for  a  considerable  time,  sufficient  tin  may  volatilize  to 
give  a  rather  conspicuous  white  coating  of  oxide,  Sn02,  on  the 
charcoal.  Tin  globules  are  readily  fusible,  malleable,  and,  if  cut, 
they  show  a  white  metallic  color.  If  treated  with  a  little,  moder- 
ately concentrated,  warm,  nitric  acid,  they  do  not  dissolve,  but  are 
oxidized  to  a  white  hydroxide  (metastannic  acid).  Tin  must  not 
be  confounded  with  other  elements  which  give  metallic  globules 
on  charcoal.  Iv  may  be  distinguished  from  lead  and  bismuth  by 
the  absence  of  a  yellow  coating  of  oxide  on  the  charcoal,  and  from 
silver  by  the  coating  of  oxide  which  forms  both  on  the  charcoal 
and  over  the  surface  of  the  globules. 

Sodium  carbonate  and  oxide  of  tin,  when  heated  together  with- 
out the  addition  of  charcoal  powder,  usually  form  an  infusible 
mass  which  is  very  difficult  to  reduce. 

2.  Oxidation  with  Nitric  Acid. — The  action  of  nitric  acid  upon  metallic 
tin  was  mentioned  in  the  previous  paragraph.     Sulphides  of  tin  (the  sul- 
phostannates),  if  pulverized  and  treated  with  nitric  acid,  yield  the  insoluble 
metastannic  acid,  and  after  evaporating  off  most  of  the  nitric  acid  and  dilut- 
ing with  water,  this  may  be  collected  on  a  filter,  washed  with  water,  and 
tested  according  to  §  1. 

3.  Detection  of  Small  Quantities  of  Tin. — Mix  1  or  2  ivory  spoonfuls  of 
the  finely  powdered  mineral  with  6  volumes  each  of  sodium  carbonate  and  of 
sulphur,  transfer  the  mixture  to  a  porcelain  crucible,  cover,  and  heat  gently 
at  first,  finally  for  five  or  ten  minutes  at  a  red  heat.     On  cooling,  treat  the 
fused  mass  with  warm  water,  which  dissolves  sodium  -sulphostannate,  while 
most  other  substances  which  are  apt  to  be  present  will  be  insoluble.     Filter, 
and  by  adding  sulphuric  acid  to  the  filtrate,  precipitate  the  tin  as  sulphide, 
which  will  be  accompanied  by  much  free  sulphur.     Collect  the  precipitate 
on  a  filter,  wash  several  times  with  water,  ignite  in  a  crucible  to  get  rid  of 
the  free  sulphur  and  the  paper,  and  test  the  residue  before  the  blowpipe  on 
charcoal,  according  to  §  1.     If  a  porcelain  crucible  is  not  at  hand,  the  fusion 
with  sodium  carbonate  and  sulphur  may  be  made  in  a  large  bulb  tube  or 
even  in  a  test-tube. 

When  niobates  and  tantalates  are  fused  with  potassium  bisulphate  and 
treated  as  directed  on  p.  99,  §  2,  the  oxides  of  tin  and  tungsten  remain  with 


Titanium  REACTIONS   OF   THE   ELEMENTS.  127 

the  niobic  and  tantalic  oxides,  and  these  may  be  separated  either  by  the 
sodium  carbonate  and  sulphur  fusion,  or  by  digestion  of  the  moist  oxides 
with  ammonium  sulphide.  After  filtering,  precipitate  the  tin  and  tungsten 
by  addition  of  sulphuric  acid,  collect  the  precipitate  on  a  filter,  wash,  ignite, 
and  test  for  tin,  as  directed  in  §  1. 

Titanium,  Ti. — Tetravalent  and  trivalent.    Atomic  weight,  48. 

OCCURRENCE. — Although  usually  classed  among  the  rare  ele- 
ments, titanium  is  quite  common,  and  is  always  found  in  combina- 
tion with  oxygen.  Kutile,  octahedrite,  and  brookite,  which  are  dif- 
ferent crystalline  forms  of  Ti02 ;  ilmenite,  or  titanic  iron  (a  com- 
bination of  the  oxides  of  iron  and  titanium);  and  titanite,  CaTiSiO5 , 
are  the  commonest  titanium  minerals.  Some  titanium,  either  in 
the  form  of  ilmenite,  titanite,  or  rutile,  is  present  in  most  igneous 
rocks. 

DETECTION. — Titanium  may  be  detected  by  the  salt  of  phos- 
phorus bead,  the  reduction  with  metallic  tin,  or  oxidation  with 
hydrogen  peroxide. 

1.  Test  with  Salt  of  PJiospJiorus. — Oxide  of  titanium,  if  dis- 
solved in  a  salt  of  phosphorus  bead  in  the  oxidizing  flame,  gives  a 
glass  which  is  yellow  when  hot,  and  colorless  when  cold,  while  in 
the  reducing  flame  the  glass  is  yellow  while  hot,  but  on  cooling 
assumes  a  delicate  violet  color,  due  to  the  presence  of  Tia03.     Since 
the  color  is  never  very  intense,  and  the  presence  of  other  sub- 
stances which  color  the  bead  interferes  with  it,  one  of  the  tests 
given  beyond  will  usually  be  found  more  satisfactory. 

No  decisive  test  can  be  made  with  borax. 

2.  deduction  with  Tin.— Most  titanium  minerals  are  very  in- 
soluble in  acids,  but  after  fusion  with  sodium  carbonate,  they  go 
readily  into  solution  in  hydrochloric  acid,  and  the  solution  con- 
tains TiCl4.    If  this  acid  solution  is  boiled  with  a  little  granulated 
tin,  the  titanium  is  reduced  to  TiCl3,  which  causes  the  solution  to 
assume  a  delicate  violet  color.     Other  substances  with  which  tita- 
nium is  apt  to  occur  do  not  interfere,  and  the  test  is  quite  delicate, 
but  if  a  substance  is  supposed  to  contain  less  than  3  per  cent  of 
TiO.,  the  test  with  hydrogen  peroxide  is  to  be  preferred. 


128  REACTIONS   OF   THE   ELEMENTS.  Titanium 

To  illustrate  this  test,  mix  ^  ivory  spoonful  of  the  fiwely  powdered  min- 
eral (rutile  or  ilmenite)  with  6  volumes  of  sodium  carbonate,  make  into  a 
paste  with  water,  and  fuse  before  the  blowpipe  either  on  platinum  wire  or 
charcoal.  Oxide  of  titanium,  which  is  an  acid  anhydride,  is  decomposed 
readily  by  sodium  carbonate,  with  formation  of  sodium  titanate,  Ti02  -{- 
2Na,CO,  =  Na4i.iO4  -t-  ^'C02.  and  the  latter  is  easily  dissolved  by  hydro- 
chloric acid.  Na4Ti04+  8HC1  =  Ti014+  4NaCl  +  4H20.  Treat  the  fusion 
in  a  test-tube  with  about  5  cc.  of  strong  hydrochloric  acid,  boil  until  a 
solution  is  obtained,  filter  if  necessary,  then  add  a  little  granulated  tin,  and 
boil  until  the  violet  color  makes  its  appearance.  If  the  quantity  of  titanium 
is  small,  it  is  necessary  to  boil  the  liquid  away  until  only  1  or  2  cc.  are  left. 
The  color  is  seen  best  when  the  acid  becomes  cold,  and  the  evolution  of 
hydrogen  ceases.  If  much  titanium  is  present,  sometimes  on  boiling,  a 
portion  of  it  will  precipitate  as  oxide,  but  enough  will  always  remain  in 
solution  to  give  the  violet  color. 

In  testing  niobates  and  tantalates  for  titanium,  it  is  best  to  fuse  the 
material  with  borax,  as  directed  on  p.  98,  §  1,  and  on  dissolving  the  fusion 
in  hydrochloric  acid  and  boiling  with  tin,  the  violet  color  of  titanium  will 
appear  before  the  blue  of  niobium. 

3.  Test  with  Hydrogen  Peroxide.—  For  this  exceedingly  defi- 
cate  test,  the  mineral  must  be  dissolved  in  sulphuric  acid,  which 
may  be  accomplished  by  first  fusing  with  sodium  carbonate,  as 
previously  directed,  treating  the  fusion  in  a  test-tube  with  1  cc.  of 
concentrated  sulphuric  acid  and  1  cc.  of  water,  and  heating  until 
the  solution  becomes  clear.  When  cold,  water  is  added,  then  some 
hydrogen  peroxide,  and  if  titanium  is  present,  the  solution  becomes 
reddish- yellow  to  deep  amber,  depending  upon  the  quantity  of  the 
titanium  in  the  solution. 

Tungsten,  W. — Sexivalent.     Atomic  weight,  185. 

OCCURRENCE. —Tungsten  is  the  acid-forming  element  in  a  group  of  min- 
erals known  as  the  tungstates,  the  most  important  of  which  are  wolframite, 
(Fe,Mn)M/r04;  hiibnerite,  MnW04;  and  scheelite, CaW04.  The  element  is 
found  in  small  quantity  in  a  number  of  the  niobates  and  tantalates. 

DETECTION. — 1.  When  a  tungstate  is  decomposed  by  boiling  with  hydro- 
chloric acid,  an  insoluble,  canary-yellow,  tungstic  oxide,  WO, ,  is  obtained, 
and  if  after  the  addition  of  a  little  granulated  tin,  the  boiling  is  continued, 
a  blue  color  is  at  first  obtained  (2WO,  4-  W09),  and  this  by  further  reduction 
finally  changes  to  brown  (WO,).  Another  very  good  way  to  test,  after 
having  decomposed  the  mineral  with  hydrochloric  acid,  is  to  collect  the 


Uranium  REACTIONS   OF   THE   ELEMENTS.  129 

W03  on  a  filter,  dissolve  some  of  it  in  ammonia,  acidify  with  hydrochloric 
acid,  which  usually  causes  a  white  or  yellowish  turbidity,  and  then  boil 
with  granulated  tin.  When  a  "blue  color  has  been  obtained,  dilute  with 
water,  when  it  will  be  found  that  the  color  does  not  disappear  (compare  Nio- 
bium), and  that  it  is  due  to  an  insoluble  compound  suspended  in  the  liquid. 

2.  If  the  tungstate  is  insoluble  or  difficultly  soluble  in  hydrochloric  acid 
(wolframite),  mix  the  fine  powder  with  6  volumes  of  sodium  carbonate,  make 
into  a  paste  with  water,  fuse  in  a  loop  on  platinum  wire,  pulverize,  and  dis- 
solve in  a  test-tube  in  a  little  water.     The  sodium  tungstate  formed  during 
fusion  is  soluble  in  water  (difference  from  niobium);  it  may  be  separated 
from  the  bases  by  filtering,  and,  on  acidifying  the  filtrate  with  hydrochloric 
acid  and  boiling  with  tin,  the  blue  reduction  test  may  be  obtained. 

3.  In  the  salt  of  phosphorus  bead  in  the  oxidizing  flame,  oxide  of  tung- 
sten gives  no  color,  but  in  the  reducing  flame,  the  bead  becomes  fine  blue. 
The  reactions  with  borax  are  not  satisfactory. 

4.  In   order  to  detect  the  small  quantity  of  tungsten  in  niobates  and 
tantalates,  treat  the  oxides  obtained  by  the  potassium  bisulphate  fusion 
(p.  99,  §  2)   either  with  ammonium  sulphide  or  a  sodium  carbonate  and 
sulphur  fusion,  separate  the  tungsten  exactly  as  described  for  tin  (p.  126, 
§  3),  and  then  test  by  the  foregoing  methods. 

Uranium,  U. — Tetravalent  and  sexivalent.  Atomic  weight 
240. 

OCCURRENCE. — This  rare  element  is  found  as  an  essential  constituent  in 
only  a  few  minerals  (uranite,  gummite,  uranosphaerite,  torbernite,  autun- 
ite),  while  it  occurs  sparingly  in  a  number  of  others,  especially  those  con 
taining  the  rare  elements  niobium,  tantalum,  thorium,  zirconium,  cerium^ 
lanthanum,  didjfffiium,  yttrium,  and  erbium;  as  fergusonite,  samarskite, 
euxenite,  and  polycrase. 

DETECTION. — 1.  The  reactions  with  the  salt  of  phosphorus  bead  usually 
serve  for  the  detection  of  uranium.  In  the  oxidizing  flame,  the  oxide  is  sol- 
uble to  a  clear  yellow  glass,  which  becomes  yellowish-green  on  cooling,  while 
after  heating  in  the  reducing  flame,  the  bead  assumes  a  fine  green  color. 
With  borax,  the  colors  are  not  so  decisive,  and  are  nearly  like  those  of  iron, 
being  in  the  oxidizing  flame  reddish-yellow  when  hot,  fading  to.  yellow 
when  cold,  and  in  the  reducing  flame,  very  pale  green,  fading  to  almost  color- 
less. 

2.  In  the  presence  of  other  elements  which  impart  color  to  the  fluxes, 
and  for  the  detection  of  small  quantities  of  uranium  in  minerals,  it  is  best 
to  proceed  as  follows  :  Make  a  solution  in  hydrochloric  acid  (after  fusion 
with  sodium  carbonate,  if  necessary,  as  directed  under  silicates,  p.  110,  §  4, 
or  with  borax,  as  directed  under  niobates,  p.  98,  §  1),  nearly  neutralize  the 
excess  of  acid  with  ammonia,  add  solid  ammonium  carbonate,  shake 


130  REACTIONS   OF   THE   ELEMENTS.  Vanadium 

vigorously,  and  allow  the  liquid  to  stand  for  a  few  minutes.  The  uranium 
is  at  first  precipitated,  but  is  soluble  in  an  excess  of  the  ammonium  carbon- 
ate, and  by  filtering  may  be  separated  from  a  great  many  elements  which 
are  precipitated  by  that  reagent.  Sometimes  there  is  difficulty  in  obtaining 
a  clear  filtrate,  and,  if  go,  a  few  drops  of  ammonium  sulphide  may  be  added 
with  the  ammonium  carbonate.  Make  the  filtrate  containing  the  uranium 
acid,  boil  to  expel  carbon  dioxide,  add  ammonia  in  excess,  collect  the  precip- 
itate containing  uranium  on  a  filter,  and  test  it  with  a  salt  of  phosphorus 
bead.  In  case  the  precipitate  is  small,  burn  the  paper  containing  it  in  a 
crucible,  and  test  the  residue. 

Vanadium,  V. — Usually  pentavalent.     Atomic  weight,  51.4. 

OCCURRENCE. — Vanadium  is  a  rare  element  found  in  the  vanadates,  or 
salts  of  vanadic  acid,  H3V04,  which  is  closely  related  chemically  to  phos- 
phoric and  arsenic  acids.  Vanadinite,  Pb4(PbCl)(V04)3,  and  descloizite, 
Pb(PbOII)V04,  are  the  commonest  vanadates. 

DETECTION. — 1.  Vanadium  is  usually  detected  by  the  color  it  imparts  to 
the  fluxes.  With  borax,  in  the  oxidizing  flame,  the  bead  is  yellow  when  hot, 
changing  through  yellowish-green  to  almost  colorless  when  cold.  In  the  re- 
ducing flame,  it  becomes  dirty  green  when  hot,  changing  to  fine  green 
when  cold.  In  the  salt  of  phosphorus  bead,  the  color  in  the  oxidizing  flame 
is  yellow  to  deep  amber,  fading  slightly  on  cooling;  while  in  the  reducing 
flame,  it  becomes  an  indistinct  dirty  green  when  hot,  changing  to  fine  green 
on  cooling.  The  amber  color  with  salt  of  phosphorus,  in  the  oxidizing 
flame,  serves  to  distinguish  vanadium  from  chromium. 

2.  To  detect  small  quantities  of  vanadium,  and  in  cases  where  other  sub- 
stances are  present  which  impart  color  to  the  fluxes,  proceed  as  follows: 
Fuse  the  powdered  mineral  in  a  platinum  spoon  with  about  4  parts  of  so- 
dium carbonate  and  2  of  potassium  nitrate,  and  digest  the  fusion  with  warm 
water,  in  order  to  dissolve  the  soluble  alkali  vanadate.  Filter,  acidify  the 
filtrate  with  a  slight  excess  of  acetic  acid,  and  add  a  little  lead  acetate, 
which  will  precipitate  a  pale  yellow  lead  vanadate  (lead  chromate,  p.  70, 
§  3,  is  much  yellower).  Some  of  the  precipitate  collected  on  a  filter-paper 
may  then  be  tested  with  a  salt  of  phosphorus  bead. 

Yttrium,  Y. — Trivalent.     Atomic  weight,  89. 

For  the  reactions  of  this  rare  element,  see  Cerium  and  the  rare  earth 
metals  (p.  65). 

Zinc,  Zn. — Bivalent.    Atomic  weight,  65.4. 

OCCURRENCE. — Zinc  occurs  most  abundantly  as  sphalerite,  ZnS, 
and  in  addition  to  this,  smithsonite,  ZnCO, ;  willemite,  Zn2SiO4 ; 


Zinc  KEACTIOJsS   OF   THE   ELEMENTS.  131 

calamine  (ZnOH)aSiO3;  and  zincite,  ZnO  with  MnO,  occur  in  suffi- 
cient quantities  to  be  mined  as  ores  of  the  metal.  Zinc  is  also 
found  in  a  number  of  other  minerals, — franklinite,  gahnite,  auri- 
chalcite,  and  in  small  quantity  in  many  sulphides. 

DETECTION. — Zinc  volatilizes  when  heated  before  the  blowpipe, 
and  is  usually  detected  by  the  coating  of  oxide  on  charcoal,  and 
also  by  the  test  with  cobalt  nitrate  and  the  flame  coloration. 

I.  Reduction  of  Zinc  to  the  Metallic  State  and  Formation  of  a 
Coating  of  Oxide.— The  best  method  for  the  detection  of  zinc  is  as 
follows  :  Mix  the  finely  powdered  mineral  with  about  j-  volume  of 
sodium  carbonate,  and  make  into  a  paste  with  water.  A  little 
of  this  mixture  is  then  taken  up  in  a  small  loop  on  fine  plat- 
inum wire  and  heated  intensely,  holding  the  loop  about  10  mm. 
from  a  piece  of  charcoal,  somewhat  as  represented  by  Fig.  49.  An 
intense  heat  and  strong  reducing 
action  are  necessary  to  bring  about 
reduction  to  the  metallic  state  and 
volatilization  of  the  zinc.  The 
metal  thus  volatilized  takes  oxy- 
gen from  the  air  and  collects  as  a 
coating  of  ZnO,  which  is  pale 
canary-yellow  when  hot  and  white 
when  cold.  The  coating  is  near 
where  the  heat  strikes  the  char- 
coal,  and  is  not  volatile  in  the 

oxidizing  flame.  If  the  coating  is  made  to  deposit  on  a  piece  of 
charcoal  previously  moistened  with  cobalt  nitrate,  the  zinc  oxide 
will  have  a  green  color  which  is  especially  characteristic. 

For  a  proper  understanding  of  this  test  it  must  be  borne  in 
mind  that  the  method  demands  the  reduction  of  zinc  to  the  metal- 
lic state,  but  no  globules  form,  for,  as  fast  as  reduced,  the  metal 
volatilizes. 

From  many  compounds,  zinc  may  be  reduced,  and  the  coating 
of  oxide  obtained  without  the  use  of  a  flux,  when  a  fragment  of 


132  REACTIONS   OF   THE   ELEMENTS.  Zinc 

the  mineral  (about  2  mm.  in  diameter)  is  heated  very  hot  on  char- 
coal in  a  reducing  flame,  but  some  skill  in  manipulating  the  flame 
is  needed  in  order  that  the  fragment  shall  not  be  blown  away. 
A  good  way  to  make  the  test  is  to  take  the  fragment  in  the  plat- 
inum forceps,  and  holding  the  latter  against  a  piece  of  charcoal  so 
that  the  assay  is  about  5  mm.  from  the  surface,  heat  at  the  tip  of 
the  blue  cone,  as  shown  in  Fig.  49. 

a.  In  order  to  make  a  zinc  oxide  coating  on  charcoal,  mix  finely  pow- 
dered calamine,  (Zn.OH).,Si03,  with  J  volume  of  sodium  carbonate,  take 
up  in  a  small  loop  on  platinum  wire  and  heat  intensely,  as  directed.  In  this 
experiment  the  sodium  carbonate  answers  a  double  purpose:  it  serves  to 
hold  the  material  on  the  platinum  wire,  and  also  to  decompose  the  silicate, 
forming  sodium  silicate,  thus  setting  free  zinc  oxide,  which  may  be  readily 
reduced.  (Zn.OH)aSiOs  +  NaaC03  =  2ZnO  +  NaaSi08  +  CO,  +  H,0. 

~b.  In  order  to  produce  the  coating  of  zinc  oxide  without  the  use  of  a 
flux,  experiment  with  fragments  of  smithsonite  or  sphalerite.  With  the  lat- 
ter mineral,  the  oxygen  of  the  air  converts  ZiiS  to  ZnO,  and  by  the  reducing 
action  of  the  flame,  zinc  oxide  is  changed  to  metallic  zinc. 

NOTE. — In  the  presence  of  lead,  bismuth,  cadmium,  or  antimony,  which 
also  give  coatings  of  oxide  on  charcoal,  the  test  for  zinc  with  cobalt  nitrate 
should  not  be  made  until  the  coating  has  been  heated  for  some  time  in  the 
oxidizing  flame,  in  order  to  volatilize  the  oxides  of  the  metals  mentioned. 

In  the  presence  of  much  tin,  it  is  difficult  to  recognize  zinc  with  cer- 
tainty by  the  reaction  on  charcoal,  as  tin  also  gives  a  white  coating  of  oxide, 
which  when  ignited  with  cobalt  nitrate  gives  a  bluish-green  color.  If,  how- 
ever, the  mineral  is  decomposed  by  nitric  acid  (stannite),  the  test  may  be 
made  as  follows  :  Treat  with  nitric  acid,  and  separate  the  tin  according  to  p. 
126,  §  2,  then  to  the  filtrate  add  solid  sodium  carbonate  until  the  acid  is 
neutralized,  and  a  permanent  precipitate  forms,  heat  to  boiling,  filter,  and 
wash  once  with  water.  The  precipitate  will  contain  all  the  zinc,  and  prob- 
ably basic  carbonates  of  other  metals,  and  a  portion  of  it,  mixed  with  sodium 
carbonate,  may  be  tested  on  charcoal  for  zinc. 

2.  Flame  Test. — From  some  minerals,  metallic  zinc  is  produced 
by  heating  in  the  platinum  forceps  in  a  strong  reducing  flame,  and 
the  metal,  as  it  volatilizes  and  passes  into  the  air,  burns  with  a 
vivid,  pale,  bluish-green  light,  appearing  usually  as  streaks  in  the 
outer  part  of  the  flame.  The  experiment  does  not  succeed  well 
when  too  small  a  fragment  is  used,  and  it  is  best  to  take  one 
about  3  mm.  in  diameter. 


Zirconium  REACTIONS   OF   THE   ELEMENTS.  133 

Experiments  may  be  made  with  smithsonite  and  sphalerite.  When  the 
former  is  used,  the  zinc  carbonate  changes  readily  to  oxide,  and,  by  reduc- 
tion, metallic  zinc  is  slowly  formed.  With  sphalerite,  the  assay  must  be  first 
converted  by  oxidation  to  zinc  oxide,  and  then  by  reduction  to  metallic  zinc, 
but  usually  a  point  can  be  found  a  little  beyond  the  blue  cone  of  the  blow- 
pipe flame,  where  oxidation  and  reduction  go  on  simultaneously,  and  a  con- 
tinuous zinc  flame  can  be  maintained. 

3.  Heating  with  Cobalt  Nitrate,  Co(NO3)a. — Some  zinc  minerals, 
when  moistened  with  cobalt  nitrate  and  heated,  assume  a  green 
color,  but  this  simple  test  can  be  applied  only  to  infusible,  white  or 
light-colored  compounds  or  those  which  become  so  on  ignition. 
In  making  the  test,  a  fragment  held  in  the  platinum  forceps  may 
be  used,  but  it  is  usually  better  to  make  the  finely  powdered  min- 
eral into  a  paste  with  cobalt  nitrate,  and  then  to  heat  on  charcoal 
in  an  oxidizing  flame. 

Silicates  of  zinc,  when  similarly  treated,  usually  show  a  blue 
color,  owing  to  the  formation  of  a  fusible  cobalt  silicate.  If  an 
experiment  is  made  with  a  large  fragment  of  calamine,  it  will  some- 
times show  blue  where  the  heat  was  most  intense,  and  green  at 
other  parts. 

4.  Change  of  Color  upon  Heating. — The  presence  of  zinc  is  often 
indicated  by  the  change  of  color  of  the  assay  when  heated  ;  i.e.,  to 
straw  or  pale  canary-yellow  when  hot,  becoming  white  when  cold. 
This  test  can,  of  course,  be  applied  only  to  compounds  which  are 
white  or  light-colored. 

Zirconium,  Zr. — Tetravalent.     Atomic  weight,  90.7. 

OCCURRENCE. — Although  a  rare  element,  zirconium  is  found  abundantly 
in  some  regions,  especially  as  zircon,  ZrSi04,  which,  in  small  quantities,  is 
almost  an  unfailing  constituent  in  granites  and  rocks  rich  in  alkalies.  It  is 
found  in  a  number  of  rare  minerals,  examples  of  which  are  baddelyite,  Zr02, 
eudialyte,  catapleiite,  wohlerite,  polymignite,  etc. 

DETECTION. — Zirconium  gives  no  very  characteristic  tests  which  serve  for 
its  quick  and  sure  identification.  A  solution  must  first  be  obtained,  which 
usually  is  accomplished  by  fusing  with  sodium  carbonate,  and  treatment  as 
directed  under  silicates  (p.  110,  §  4).  The  decomposition,  however,  is  not 
complete,  and  usually  only  a  portion  of  the  zirconium  will  be  obtained  in 
solution.  The  simplest  test  is  with  turmeric-paper,  which,  when  placed  in  a 


134  REACTIONS   OF   THE   ELEMENTS.  Zirconium 

hydrochloric  acid  solution  containing  zirconium,  assumes  an  orange  color. 
As  the  color  is  not  very  marked,  it  is  best  to  make  a  comparison  by  taking 
two  test-tubes,  one  containing  turmeric-paper  wet  by  the  solution  containing 
zirconium,  and  the  other  a  paper  wet  by  acid  of  about  equal  strength. 

Ammonium,  sodium,  and  potassium  hydroxide  throw  down  zirconium 
hydroxide  as  a  bulky,  gelatinous  precipitate,  insoluble  in  an  excess  of  so- 
dium and  potassium  hydroxides,  thus  differing  from  aluminium  and  beryl- 
lium. The  precipitate  is  filtered,  washed  with  water,  dissolved  in  a  little 
hydrochloric  acid,  the  solution  evaporated  until  only  a  drop  or  two  of  the 
acid  remains,  the  residue  dissolved  in  water,  and  oxalic  acid  added,  when,  if 
zirconium  alone  is  present,  either  no  precipitate  forms,  or,  if  it  does  form,  it 
goes  almost  immediately  into  solution  (difference  from  the  rare  earth  metals, 
cerium,  lanthanum,  etc.,  p.  65).  A  portion  of  zirconium  hydroxide  found 
by  the  previous  test  to  contain  no  rare  earth  metals,  or  separated  from  them 
by  means  of  oxalic  acid,  may  be  scraped  from  the  filter-paper,  and  dissolved 
in  the  least  possible  amount  of  dilute  sulphuric  acid  ;  to  the  solution,  pot- 
assium hydroxide  is  then  added  until  a  precipitate  forms,  afterwards  dilute 
sulphuric  acid  is  added  a  drop  at  a  time,  until  the  solution  clears  (if  care- 
fully done  the  liquid  at  this  point  will  be  nearly  neutral,  and  the  volume 
should  be  small);  finally,  a  little  more  than  an  equal  volume  of  a  boiling, 
saturated  solution  of  potassium  sulphate  is  added,  which  on  standing  pre- 
cipitates a  double  zirconium  potassium  sulphate  as  a  white  powder,  and 
serves  as  a  characteristic  test  for  zirconium,  although  the  precipitation  is  not 
complete.  If  the  precipitate  is  filtered,  and  washed  with  a  cold  and  satu- 
rated solution  of  potassium  sulphate,  then  dissolved  in  warm  hydrochloric 
acid,  pure  zirconium  hydroxide  may  be  precipitated  by  means  of  ammonia. 
On  ignition,  zirconium  hydroxide  yields  the  oxide  Zr02,  and  this,  if  pulver- 
ized, mixed  with  cobalt  nitrate,  and  ignited  before  the  blowpipe  on  charcoal, 
assumes  a  lavender  or  bluish  slate-color. 


CHAPTER  IV. 

TABULATED  ARRANGEMENT  OF  THE  MORE  IMPORTANT  BLOWPIPE  AND 

CHEMICAL  REACTIONS. 

THIS  chapter  is  intended  to  be  used  especially  for  the  interpre- 
tation of  unknown  reactions  which  are  encountered  in  blowpipe 
analysis.  The  tests,  if  made  in  the  order  given  below,  will  serve  as 
a  systematic  course  of  qualitative  blowpipe  analysis  in  examining 
unknown  substances. 

A.  Heating  in  the  platinum  forceps  :  Flame  coloration,  p.  135. 

B.  Heating  in  the  closed  tube,  p.  137. 

C.  Heating  in  the  open  tube,  p.  140. 

D.  Heating  on  charcoal,  both  with  and  without  fluxes,  p.  142. 

E.  Treatment  with  cobalt  nitrate,  p.  146. 

F.  Fusion  with  the  fluxes  on  platinum  wire :  Borax,  p.  148 ; 
phosphorus  salt,  p.  149  ;  and  sodium  carbonate  beads,  p.  151. 

G.  Treatment  with   acids,    and    reactions  with    the    common 
reagents,  p.  151. 

A.  HEATING  IN  THE  PLATINUM   FORCEPS  :   FLAME  COLORATION. 

Suggestions  concerning  the  use  of  the  platinum  forceps  and  the 
methods  of  heating  substances  in  them  have  been  given  in  Chapter 
II,  p.  15.  In  testing  minerals,  any  change  which  the  material 
undergoes  should  be  carefully  noted,  but  for  the  identification  of 
the  elements,  flame  colorations  are  the  most  important.  The  colors 
may  often  be  obtained  best  by  heating  on  platinum  wire,  as  sug- 
gested on  p.  35. 

If  a  black,  magnetic  globule  or  mass  is  obtained  after  heating 
in  the  reducing  flame,  it  usually  indicates  iron,  less  often  cobalt 

135 


136 


IMPORTANT  BLOWPIPE   AND   CHEMICAL   REACTIONS. 


or  nickel.  If  the  mass  left  in  the  forceps  after  heating  before 
the  blowpipe  gives  an  alkaline  reaction  when  placed  on  mois- 
tened turmeric-paper,  it  indicates  the  presence  of  an  alkali  or 
alkaline  earth;  as  sodium,  potassium,  calcium,  strontium,  'barium, 
and  possibly  magnesium. 

TABLE  OF   FLAME   COLORATIONS. 


Color. 

Shade  or 
Tone. 

Element. 

Remarks. 

Bed. 
Ked. 

Crimson. 

Lithium. 

The  lithia  minerals,  which  are  either  silicates 
or  phosphates,  do  not  become  alkaline  after 
ignition  (difference  from  strontium). 

Crimson. 

Strontium. 

Carbonates  and  sulphates  show  the  reaction, 
and  become  alkaline  after  ignition.  Sili- 
cates and  phosphates  do  not  give  the  stron- 
tium flame. 

Ked. 

Yellowish 
to  orange. 

Calcium. 

Only  a  few  minerals  give  this  color  decisively 
when  heated  alone.  Often,  however,  the 
color  shows  distinctly  after  moistening  the 
assay  with  hydrochloric  acid. 

Yellow. 

Intense. 

Sodium. 

This  test  is  so  delicate  that  great  care  must  be 
exercised  in  using  it  (compare  p.  115). 

Green. 

Yellowish. 

Barium. 

Carbonates  and  sulphates  show  the  reaction, 
and  become  alkaline  after  ignition.  Sili- 
cates and  phosphates  do  not  give  the  barium 
flame. 

Green. 

Yellowish. 

Molybdenum. 

If  in  the  form  of  oxide  or  sulphide. 

Green. 

Bright, 
somewhat 
yellowish. 

Boron. 

The  test  with  turmeric-paper  in  hydrochloric 
acid  solution  is  decisive.  The  compounds 
rarely  show  an  alkaline  reaction  after  igni- 
tion. 

Green. 

Pure. 

Thallium. 

Green. 

Emerald. 

Copper    oxide 
and  iodide. 

After  moistening  the  assay  with  hydrochloric 
acid,  the  flame  appears  azure-blue,  tinged 
with  green. 

Green. 
Green. 

Pale  bluish. 

Phosphorus. 

The  color  is  not  very  decisive,  but  often  aids 
in  the  identification  of  a  phosphate. 

Bluish. 

Zinc. 

Appears  usually  as  bright  streaks  in  the 
flame. 

Green. 

Pale. 

Tellurium. 
Antimony. 
Lead. 

IMPORTANT    BLOWPIPE   AND    CHEMICAL   REACTIONS. 
TABLE  OF  FLAME  COLORATIONS. —  Continued. 


137 


Color. 

Shade  or 
Tone. 

Element. 

Remarks. 

Blue. 

Azure. 

Copper  chlo- 
ride. 

The  outer  darts  of  the  flame  are  tinged 
emerald-green. 

with 

Blue. 

Azure. 

Selenium. 

Accompanied  by  a  characteristic  odor. 

Blue. 
Blue. 

Pale  azure. 

Lead. 

Perceptibly  tinged   with  green  in  the 
parts. 

outer 

Indium. 

Blue. 

Pale. 

Arsenic. 

Blue. 

Greenish. 

Phosphorus. 
Antimony. 

Violet. 

Pale. 

Potassium. 
Rubidium. 
Caesium. 

B.  HEATING  IN  THE  CLOSED  TUBE. 

Closed  tubes  and  the  nature  of  the  reactions  which  may  be  ob- 
tained in  them  have  been  explained  on  p.  18.  The  phenomena 
which  are  to  be  especially  observed  are  as  follows  : 

a.  Change  in  the  condition  or  appearance  of  the  assay. 

b.  The  formation  of  gases  which  collect  in  the  tube. 

c.  The  formation  of  sublimates,  liquid  or  solid,  which  condense 
on  the  cold  walls  of  the  tube. 

a.  Change  in  tlie  Condition  or  Appearance  of  the  Assay. 

1.  FUSION. — Only  substances  which  melt  very  easily,  below  \\ 
in  the  scale  of  fusibility,  fuse  in  the  closed  glass  tube. 

2.  DECREPITATION. — Fragments  of  decrepitating  minerals  (com- 
pare p.  34)  snap  and  explore,  and  often  break  up  into  very  fine 
powder  or  dust. 

3.  PHOSPHORESCENCE  AND   GLOWING. — Some  minerals  when 
heated  to  a  temperature  below  redness  emit  a  bright,  often  beau- 
tifully colored  light,  which  may  continue  for  a  considerable  time, 


138 


IMPORTANT  BLOWPIPE   AND   CHEMICAL   REACTIONS. 


and  is  seen  best  in  a  dark  room.    A  very  few  minerals  glow,  as  if 
they  had  taken  fire. 

4.  CHANGE  OF  COLOR. — Materials  often  change  color  after 
heating,  owing  to  decomposition.  Again,  without  any  change  in 
chemical  composition,  some  substances  when  hot  assume  colors 
which  are  different  from  those  they  have  when  cold.  The  changes 
are  very  numerous,  and  only  a  few  of  the  more  important  are  given. 


TABLE  GIVING  CHANGE  OF   COLOR  IN    SUBSTANCES   WHEN  HEATED 

IN   THE   CLOSED   TUBE. 


Original  Color. 

Color  after  Heating. 

Substance. 

Remarks. 

Hot. 

Cold. 

Green  or  blue. 

Black. 

Black. 

Copper  minerals. 

These  changes  usually 
occur  when  oxides  of 
the  metals  result  from 
the  decomposition  due 
to  heating. 

Green  or  brown. 

Black. 

Black. 

Iron  minerals. 

Pink. 

Black. 

Black. 

Manganese      and 
cobalt  minerals. 

Dark  red. 

Black. 

Dark  red. 

Ferric  oxide. 

White  or  color- 
less. 

Dark     yel- 
low     to 
brown. 

Pale  yellow 
to  white. 

Lead     and      bis- 
muth minerals. 

White  or  color- 
less. 

Pale  cana- 
ry-yel- 
low. 

White. 

Zinc  minerals. 

b.  The  Formation  of  Gases  which  Collect  in  the  Closed  Tube. 

1.  CARBON  DIOXIDE,  CO,. — Colorless  and  odorless.     May  be 
identified  by  introducing  a  drop  of  barium  hydroxide  into  the 
tube  (p.  64,  §  2).     Obtained  from  most  carbonates. 

2.  SULPHUR  DIOXIDE,    S02.— Colorless,  with  strong,  pungent 
odor.    It  is  further  characterized  by  the  acid  reaction  it  imparts  to 
moistened  blue  litmus-paper.    Formed  from  the  decomposition  of 
some  sulphates,  and  in  small  quantities,  also,  when  sulphides  are 
heated,  owing  to  the  air  in  the  tube. 

3.  OXYGEN,  O. — Colorless  and  odorless,  but  may  be  detected  as 


IMPORTANT   BLOWPIPE   AND   CHEMICAL   REACTIONS. 


139 


described   on  p.    100,    §  1.     Formed  when  some  higher  oxides, 
especially  those  of  manganese,  are  heated. 

4.  AMMONIA,  NH8. — Colorless,  with  characteristic  odor. 

5.  HYDROFLUORIC  ACID,  HF. —Colorless,  with  pungent  odor, 
etching  of  the  glass,  and  strong  acid  reaction.     From  compounds 
containing  fluorine  with  hydroxyl  (p.  77,  §  5). 

6.  NITROGEN  DIOXIDE,  NOa. — Red  vapors,  with  pungent  odor. 
From  nitrates. 

7.  BROMINE,  Br. — Red  vapors,  with  pungent  odor. 

8.  IODINE,  I. — Violet  vapors,  often  accompanied  by  crystals  of 
iodine. 

9.  BROWN  SMOKE,  accompanied  by  dark  distillation  products 
and  empyreumatic  odor.     Organic  material. 

c.  The  Formation  of  Sublimates  which  Condense  on  the  Walls 

of  the  Tube. 

TABLE  OF  SUBLIMATES  PRODUCED  IN  THE  CLOSED  TUBE. 


Color  and  Condition. 

Substance. 

Remarks. 

Hot. 

Cold. 

Colorless    liquid; 
easily  volatile. 

Colorless  liquid. 

Water,  H3O. 

From  all  minerals  containing 
water  of  crystallization  and 
hydroxyl.  Neutral  if  pure, 
but  may  be  acid  from  hydro- 
fluoric, sulphuric,  and  hy- 
drochloric, or  other  volatile 
acid.  Earely  alkaline  from 
ammonia. 

Pale     yellow    to 
colorless  liquid; 
difficultly  vola- 
tile. 

Colorless  to  white 
globules. 

Tellurous    oxide, 
TeO3. 

From  tellurium  and  a  few  of  its 
compounds. 

Red  to  dark  yel- 
low         liquid; 
readily  volatile. 

Yellow  and  crys- 
talline solid; 
nearly  white 
when  in  small 
quantity. 

Sulphur,  S. 

From  native  sulphur  and  some 
sulphides  (p.  119,  §4). 

Continued. 


140  IMPORTANT   BLOWPIPE   AND   CHEMICAL   REACTIONS. 

TABLE  OF  SUBLIMATES  PRODUCED  IN   THE   CLOSED   TUBE. —  Continued. 


Color  and  Condition. 

Substance. 

Remarks. 

Hot. 

Cold. 

Deep  red,  almost 
black      liquid; 
readily  volatile. 

Reddish-yellow, 
transparent 
solid. 

Sulphides  of  ar- 
senic. 

From  realgar,  AsS,  orpiment, 
As2S3  ,  and  some  compounds 
containing  sulphur  and  ar- 
senic, the  sulpharsenites. 

Black;   difficultly 
volatile,  solid. 

.Reddish-brown. 

Oxysulphide      oi 
antimony, 
Sb2OS2. 

From  sulphide  of  antimony  and 
some  of  its  compounds  with 
metallic  sulphides,  the  sulph- 
antimonites. 

Brilliant  black,  solid  ;   often  gray 
and  crystalline  near  the  heated 
<end. 

Arsenic,  As. 

From  native  arsenic  and  some 
arsenides.  If  the  tube  is 
broken  off  below  the  deposit 
and  the  arsenic  volatilized, 
the  characteristic  garlic  odor 
may  be  obtained. 

Brilliant  black,  solid. 

Sulphide  of  mer- 
cury, HgS. 

[f  a  little  of  the  sublimate  is 
removed  and  rubbed  very 
fine,  it  yields  a  red  powder. 

Black     fusible     globules.        The 
smallest  ones  transmit  a  reddish 
light. 

Selenium,  Se. 

From  selenium  and  some  sele- 
nides.  Usually  accompanied 
by  crystals  of  selenious 
oxide,  SeO3.  ' 

Black  fusible  globules. 

Tellurium,  Te. 

From  tellurium  and  some  tel- 
lurides.  Usually  accompanied 
by  fused  globules  of  tellurous 
oxide,  TeO2. 

Gray  metallic  globules,  which  may 
be    united   by  rubbing  with  a 
strip  of  paper. 

Mercury,  Hg. 

From  native  mercury  and 
amalgams. 

White,  solid. 

Chlorides  of  lead 
and  antimony. 
Oxides  of  arsenic 
and  antimony. 
Ammonia  salts. 

C.  HEATING  IN  THE  OPEN  TUBE. 

Open  tubes,  the  methods  of  manipulation,  and  the  nature  ox 
the  reactions  which  may  be  obtained  in  them,  have  been  explained 
on  p.  18.  The  phenomena  which  are  to  be  especially  observed 
are  as  follows : 


IMPORTANT   BLOWPIPE    AND   CHEMICAL    REACTIONS. 


141 


a.  Odors. 

b.  The  formation  of  sublimates  which  condense  on  the  walls  of 
the  tube. 

c.  The  character  of  the  residues. 

a.  Odors. 

1.  ODOR  OF  BURNING  SULPHUR. — Very  strong  and  pungent, 
due  to  oxidation  and  formation  of  sulphurous  anhydride,  SO2.     A 
piece  of  moistened,  blue  litmus-  paper  placed  in  the  upper  end  of 
the  tube  is  reddened,  owing  to  the  acid  character  of  S02.    If  prop- 
erly oxidized,   no  sublimate  of  sulphur  is  formed.     The  test  is 
exceedingly  delicate,  and  is  useful  for  the  identification  of  sul- 
phides. 

2.  GARLIC  ODOR. — Observed  when  arsenic  is  driven  off  rapidly 
from  its  compounds,  and  is  not  completely  oxidized. 

3.  ODOR  OF  SELENIUM. — A  peculiar  odor,  learned  only  by  ex- 
perience.     Obtained  when  selenium  is  volatilized  from  its  com- 
pounds and  not  wholly  oxidized. 

4.  ODOR  OF  OSMIC  OXIDE. — Very  pungent. 

b.  Sublimates. 

TABLE   OF   SUBLIMATES   PRODUCED   IN   THE   OPEN  TUBE. 


•Color  and  Character. 

Substance. 

Remarks. 

Black;  volatile. 

Arsenic  and  sulphide 
of  mercury. 

These  sublimates  frequently  result  from 
too  rapid  heating  of  minerals  contain- 
ing arsenic,  mercury,  antimony,  and 
sulphur,  but  they  will  not  form  if  the 
open-tube  test  is  made  properly,  with 
sufficient  draft,  so  that  the  oxidation 
is  complete. 

Brown. 

Oxysulphide  of   an- 
timony. 

Yellow    or    orange; 
easily  volatile. 

Sulphur     and     sul- 
phides of  arsenic. 

Red;  volatile. 

Selenium,  Se. 

Often  accompanies  selenious  oxide  (see 
below). 

Pale     yellow    when 
hot;    white   when 
cold. 

Molybdenum    triox- 
ide,  MoO3. 

Forms  slowly  when  molybdenum  oxide 
or  sulphide  is  heated,  and  collects  near 
the  assay  as  a  network  of  delicate  crys- 
tals. 

Continued. 


142  IMPORTANT   BLOWPIPE   AND   CHEMICAL    REACTIONS. 

TABLE   OF   SUBLIMATES   PRODUCED   IN   THE   OPEN    TUBE.  —  Continued. 


Color  and  Character. 

Substance. 

Remarks. 

White;  readily  vol- 
atile and  crystal- 
line. 

Arsenious        oxide, 

As2O3. 

The  sublimate  forms  as  a  ring,  and  where 
it  deposits  on  the  warm  glass  it  is 
distinctly  crystalline  (octahedrons). 

White;  readily  vol- 
atile and  crystal- 
line. 

Selenious         oxide. 
Se02. 

The  sublimate  usually  appears  as  radi- 
ating, prismatic  crystals,  often  ac- 
companied by  a  little  finely  diviuwd 
selenium,  which  is  red. 

White  to  pale  yellow 
globules  ;  slowly 
volatile. 

Tellurous         oxide, 
Te03. 

White;  slowly  vol- 
atile and  crystal- 
line. 

Antlmonious  oxide, 
Sb203. 

Obtained  from   antimony  and   its  com 
pounds,  which  do  not  contain  sulphur 
The  sublimate  consists  of  two  kinds  ol 
crystals,       octahedrons,       resembling 
As2O3  ,  and  prisms. 

Pale  straw  -  yellow 
when  hot;  white 
when  cold;  in- 
fusible, non-  vol- 
atile, and  amor- 
phous. 

Antimonate  of  anti- 
mony, SbaOi. 

Obtained  from  sulphide  of  antimony  and 
sulphantimonites,  as  a  dense  white 
smoke,  which  passes  up  the  tube  and 
settles  mostly  on  the  under  side.  This 
sublimate  is  usually  accompanied  by 
the  volatile  one  of  Sb2Os. 

White  ;  non-volatile 
and  infusible. 

Sulphite    and     sul- 
phate of  lead. 

Obtained  from  sulphide  of  lead  as  a 
slight  deposit,  collecting  mostly  on  the 
lower  side  of  the  tube  near  the  assay. 

Gray  metallic  glob- 
ules; volatile. 

Mercury,  Hg. 

By  rubbing  the  minute  globules  with  a 
strip  of  paper,  they  may  be  made  to 
unite. 

c.  The  Character  of  the  Residue. 

The  residue  left  after  heating  in  an  open  tube  is  usually  an 
oxide,  and  if  saved,  it  may  often  be  found  very  useful,  especially 
for  treatment  with  the  fluxes  on  platinum  wire  or  reduction 
on  charcoal. 

D.  HEATING  ON  CHARCOAL. 

Suggestions  concerning  the  use  of  charcoal,  and  the  manner  in 
which  tests  should  be  made,  have  been  given  on  p.  39.  The 
phenomena  which  are  to  be  especially  observed  are  : 

a.  Odors. 


IMPORTANT   BLOWPIPE   AND    CHEMICAL   REACTIONS. 


143 


b.  Sublimates. 

c.  The  formation  of  metallic  globules  or  of  a  magnetic  mass. 


etc. 


a.  Odors. 


1.  ODOR  OF  BURNING   SULPHUR. — Obtained  by  roasting  sul- 
phides in  the  oxidizing  liame. 

2.  ODOR  OF  GARLIC. — Obtained  by  heating  native  arsenic  and 
arsenides  in  the  reducing  flame. 

3  ODOR  OF  SELENIUM.  —  A  peculiar  odor,  which  must  be 
learned  by  experience.  Obtained  when  selenium  is  volatilized 
from  its  compounds  in  the  reducing  flame. 

b.  Sublimates. 

TABLE   OF   SUBLIMATES    PRODUCED   ON   CHARCOAL. 


Color  and  Character. 

Substance. 

Remarks. 

Near  the  Assay. 

Distant  from 
the  Assay. 

White  ;    very  vol- 
atile,           and 
mostly    distant 
from  the  assay. 

White  to  gray- 
ish. 

Arsenious  ox- 
ide, ASaOa. 

Obtained  when  arsenic,  its  sul- 
phides, and  the  arsenides  are 
roasted  in  the  oxidizing  flame. 
Often  the  garlic  odor  is  pro- 
nounced. 

Steel-gray  ;    faint 
metallic  luster, 
and  very   vola- 
tile. 

White,frequent- 
ly  tinged 
with  red. 

Seleniousoxide, 
SeO2.  The 
red  is  Se. 

Obtained  by  roasting  selenides  in 
the  oxidizing  flame.  The  sub- 
limate when  touched  with  the 
reducing  flame  imparts  an  azure- 
blue  color  to  the  flame.  The 
selenium  odor  is  pronounced. 

White;  very  vola- 
tile and  mostly 
distant  from  the 
assay. 

White  and  not 
very  pro- 
nounced. 

Oxide  of  thal- 
lium, T12O. 

The  sublimate  heated  in  the  re- 
ducing flame  volatilizes,  and 
imparts  a  green  color  to  the 
flame. 

Dense  white;  vol- 
atile. 

Gray,  some- 
times slightly 
brownish. 

The  white  is 
tellurous  ox- 
ide,Te02.  The 
gray  is  Te. 

The  sublimate  heated  in  the  re- 
ducing flame  volatilizes,  and 
imparts  a  green  color  to  the 
flame. 

Continued. 


144  IMPORTANT    BLOWPIPE    AND    CHEMICAL    REACTIONS. 

TABLE   OF   SUBLIMATES   PRODUCED   ON   CHAUCOAL. —  Continued. 


Color  and  Character. 

Substaiice. 

Remarks. 

Near  the  Assay.       D^^ 

Dense  white;  vol- 
atile,   and    de- 
posits        quite 
near  the  assay. 

Bluish. 

Oxides  of  anti- 
mony, Sb2O3 
and  Sb2O4. 

Obtained  when  antimony 
oxides  and  sulphides  are 
in  the  oxidizing  flume. 

and  its 
roasted 

White  coatings  may  also  result  from  the  volatilization  of  a  variety  of  compounds, 
especially  chlorides  of  copper,  lead,  mercury,  ammonium,  and  the  alkalies. 


Canary    -    yellow 
when  hot;  white 
when  cold.  Not 
volatile   in    the 
oxidizing  flame. 

Faint  white. 

Oxide  of  zinc, 
ZnO. 

By  heating  some  zinc  minerals  in 
the  reducing  flame,  metallic  zinc 
is  produced,  which  volatilizes, 
becomes  oxide,  and  condenses 
on  the  coal.  If  the  coating  is 
moistened  with  cobalt  nitrate 
and  ignited,  it  becomes  green. 

Faint    yellow    to 
white  when  hot; 
'    white         when 
cold.    Not  vol- 
atile in  the  oxi- 
dizing flame. 

Faint  white. 

Oxide  of  tin, 
SnOa. 

The  coating  moistened  with  cobalt 
nitrate  and  ignited  assumes  a 
bluish-green  color. 

•  /•_.  .V 

Pale  yellow  when 
hot;  white  when 
cold;  sometimes 
distinctly  crys- 
talline.     Vola- 
tile in  the  oxi- 
dizing flame. 

Bluish. 

Oxide      of  mo- 
lybdenum, 
MoO3. 

The  coating  if  touched  for  an  in- 
stant with  the  reducing  flame 
assumes  a  beautiful  azure-blue 
color.  A  copper-red  sublimate 
of  MoO2  deposits  nearer  the 
assay  than  the  MoO3  coating. 

Yellow  when  hot  ; 
straw   -  yellow 
when  cold.  Vol- 
atile    in     both 
the      oxidizing 
and      reducing 
flames. 

Dense      white, 
with    bluish- 
white  border. 

A  mixture  of 
oxide,  sul- 
phite, and 
sulphate  of 
lead. 

This  sublimate,  strongly  resem- 
bling that  of  antimony,  forms 
when  galena  and  other  sulphides 
of  lead  are  heated  very  hot  on 
charcoal. 

Dark  yellow  when 
hot;       sulphur- 
yellow        when 
cold.      Volatile 
in  both  the  oxi- 
dizing  and   re- 
ducing flames. 

Bluish-white. 

Oxide  of  lead, 
PbO. 

The  coating  when  moistened  with 
hydriodic  acid  and  heated  is 
changed  to  volatile,  yellowish- 
green  lead  iodide. 

IMPOKTANT   BLOWPIPE   AND   CHEMICAL   REACTIONS.  145 

TABLE   OF   SUBLIMATES   PRODUCED   ON  CHARCOAL. — Continued. 


Color  and  Character. 

Substance. 

Remarks. 

Near  the  Assay. 

Distant  from 
the  Assay. 

Dark   orange-yel- 
low when  hot  ; 
orange  -  yellow 
when  cold.  Vol- 
atile    in     both 
the      oxidizing 
and      reducing 
flames. 

Greenish-white. 

Oxide  of  bis- 
muth, Bi203. 

The  coating  when  moistened  with 
hydriodic  acid  and  heated  is 
changed  to  volatile,  chocolate- 
brown  bismuth  iodide. 

Dark,          almost 
black;  changing 
in     short     dis- 
tance   to    red- 
dish   -    brown. 
Volatile  in  both 
the      oxidizing 
and      reducing 
flames. 

Yellow. 

Cadmium  ox- 
ide, CdO. 

When  it  forms  a  very  thin  deposit, 
the  coating  often  shows  an  iri- 
descence resembling  peacock 
colors. 

Keddish    to  deep 
lilac. 

Silver  when  ac- 
companied by 
lead  and  anti- 
mony. 

Pure  silver  when  heated  alone  on 
charcoal  for  a  long  time  gives  a 
slight  brownish  coating. 

c.  The  .Formation  of  Metallic  Globules  or  of  a  Magnetic 

Mass,  etc. 

In  order  to  obtain  metallic  globules,  the  powder  is  usually 
mixed  with  sodium  carbonate,  and  heated  in  the  reducing  flame. 

1.  GOLD. — Rather  easily  fusible ;  bright  when  hot  and  cold ; 
no  coating  on  the  charcoal ;  color,  yellow  ;  malleable. 

2.  SILVER. — Rather  easily  fusible  ;  bright  when  hot  and  cold  ; 
no  conspicuous  coating  on  the  charcoal ;  color,  white  ;  malleable. 

3.  COPPER. — Fusible  at  a  rather  high  heat ;  bright  when  in  the 
reducing  flame,  but  oxidizing  and  becoming  black  on  exposure  to 
the  air  ;  no  coating  on  the  charcoal ;  color,  red  ;  malleable. 

4.  LEAD. — Easily  fusible  ;  bright  when  in  the  reducing  flame, 
but  oxidizing  on  exposure  to  the  air ;  a  yellow  coating  of  oxide  of 


146  IMPORTANT   BLOWPIPE   AND   CHEMICAL   REACTIONS. 

lead  deposits  on  the  charcoal ;  the  metal  has  a  lead-gray  color, 
and  is  soft  and  malleable. 

5.  BISMUTH. — Easily  fusible;    bright   when  in  the   reducing 
flame,  but  oxidizing  on  exposure  to  the  air ;  a  yellow  coating  of 
oxide  of  bismuth  deposits  on  the  charcoal ;  the  metal  has  a  lead- 
gray  color,  and  is  brittle,  although  it  may  at  first  flatten  to  some 
extent  when  hammered. 

6.  TIN. — Easily  fusible ;   bright  when  in  the  reducing  flame, 
but  oxidizing  on  exposure  to  the  air ;  a  white  coating  of  oxide  of 
tin  deposits  on  the  charcoal  if  the  globule  is  heated  intensely  ; 
the  metal  has  a  white  color,  and  is  soft  and  malleable. 

7.  EASILY    FUSIBLE    G-LOBULES    with  metallic  luster,    bright 
when  in  the  reducing  flame,  but  tarnishing  on  exposure  to  the  air, 
are  frequently  obtained  when  combinations  of  the  metals  with 
sulphur,  arsenic,  or  antimony  are  heated  on  charcoal.       These 
globules  of  sulphide,  arsenide,  or  antimonide  of  the  metals  may 
usually  be  distinguished  from  pure  metals  by  their  brittleness. 

8.  MAGNETIC  GLOBULES  or  a  magnetic  mass  will  be  obtained 
when  substances  containing  iron,  less  often  cobalt  and  nickel,  are 
fused  with  sodium  carbonate  on  charcoal. 

9.  ALKALINE  REACTION. — Provided  sodium  carbonate  has  not 
been  used  as  a  flux,  a  mass  or  residue,  which,  after  strong  igni- 
tion,  gives  an  alkaline  reaction  when    placed   upon  moistened 
turmeric-paper  indicates   one  of  the  alkalies  or  alkaline  earths; 
as  sodium,  potassium,  calcium,  strontium,  barium,  and  possibly 
magnesium. 

10.  BLACKENS  SILVER.— After  fusion  with  sodium  carbonate 
in  the  reducing  flame  and  placing  upon  a  clean,  moistened  silver 
surface,  if  a  black  stain  is  produced,  it  indicates  some  compound 
of  sulphur  (p.  119,  §  5,  and  p.  122,  §  2). 

E.  TREATMENT  WITH  COBALT  NITRATE. 

The  method  of  testing  with  cobalt  nitrate  has  been  given  on 
p.  29.  It  is  applicable  only  to  infusible  and  light-colored  com 
pounds,  and  is  especially  useful  in  detecting  zinc  and  aluminium. 


IMPORTANT   BLOWPIPE   AND   CHEMICAL    REACTIONS. 


TABLE   OF    REACTIONS   WITH   COBALT   NITRATE. 


147 


Color. 

Substance. 

Remarks. 

Pale  pink  or  flesh- 
color. 

Magnesia,  MgO,  and  salts 
containing  it. 

The  color  is  obtained  only  when  very 
pure  compounds  are  tested,  and  is 
not  very  decisive. 

Green  ;   seen  best 
when  cold. 

Oxide  of  zinc,  ZnO,  and 
compounds    containing 
it. 

The  test  may  be  applied  to  fragments 
of   minerals   or   to   the  coating  of 
zinc  oxide  on  charcoal. 

Bluish-green. 

Oxide  of  tin,  SnO2. 

Observed  when  a  coating  on  charcoal 
is  tested. 

Ultnimarine-blue. 

Aluminium  oxide,  A12O3, 
and  compounds  contain- 
ing it. 

About   the  best  test  for  aluminium, 
but    must    not    be    mistaken    for 
silicate  of  zinc. 

Ultramarine-  blue. 

Silicates  of  zinc. 

Due  to  a  fusible  silicate  of  cobalt. 

Dirty  green. 

Oxide  of  antimony. 

1 

Yellowish-green. 

Oxide  of  titanium. 

These  colors  are  rather  indistinct, 

Violet, 

Oxide  of  silicon,  quartz. 

f     and  not  very  satisfactory. 

Lavender. 

Oxide  of  beryllium. 

j 

F.  FUSION  WITH  THE  FLUXES  ON  PLATINUM  WIEE. 
These  tests  may  be  divided  into  three  heads  as  follows : 

a.  Fusion  with  borax. 

b.  Fusion  with  salt  of  phosphorus. 

c.  Fusion  with  sodium  carbonate. 

It  should  be  borne  in  mind  that  the  colors  given  in  the  follow- 
ing tables  are  those  which  the  pure  oxides  of  the  metals  yield 
when  dissolved  in  the  fluxes,  but  it  would  be  almost  impossible  to 
tabulate  all  the  varieties  of  color  given  by  mixtures  of  the  oxides. 
If  a  substance  which  is  to  be  tested  is  not  an  oxide,  it  may  be 
frequently  brought  into  that  condition  by  roasting  on  charcoal  or 
in  an  open  tube. 

Too  much  pains  cannot  be  taken  in  making  the  beads  of  suit- 
able size,  about  3  mm.  in  diameter,  introducing  the  proper  amount 
of  material  into  them,  and  heating  successfully  both  in  the  oxidiz- 
ing and  reducing  flames.  Suggestions  about  making  beads  and 
fusing  substances  in  them  have  been  given  on  pp.  16,  24,  and  25. 


148  IMPORTANT   BLOWPIPE   AND   CHEMICAL   REACTIONS. 

a.  Fusion  with  BORAX  on  Platinum  Wire. 

TABLE   OF    REACTIONS    OBTAINED    WITH    BORAX. 


Oxidizing  Flame. 

Amount 
of 
Material. 

Produced  by 

Reducing  Flame. 

Hot. 

Cold. 

Hot.                    Cold. 

Colorless, 

Colorless. 

^ittle  or 
much. 

Oxides  of  silicon,  al- 
uminium, and  tin. 

Colorless.     Colorless. 

Colorless 

Colorless        or 
opaque  white, 
depending  up- 
on the  degree 
of  saturation. 

^ittle  or 
much. 

Oxides  of   calcium, 
strontium,  barium, 
magnesium,  beryl- 
lium, zinc,  yttrium, 
lanthanum,    thori- 
um,        zirconium, 
tantalum,  and  co- 
lumbium. 

Colorless.    , 

1 

Colorless     or 
opaque  white, 
depending 
upon  the  de- 
gree of  satu* 
ration. 

Pale  yellow. 

Colorless  or 
white. 

Much. 

Oxides  of  lead,  an- 
timony, and  cad- 
mium. 

Pale 
yellow. 

Colorless. 

Pale  yellow. 

Colorless  or 
white. 

Much. 

Oxide  of  bismuth. 

Gray. 

Gray. 

Fale  yellow. 

Colorless  or 
white. 

Much. 

Oxide  of   molybde- 
num. 

Brown. 

Brown. 

Pale  yellow. 

Colorless  or 
white. 

Medium. 

Oxide  of  tungsten. 

Yellow. 

Yellow  to  yel- 
owish  brown. 

Pale  yellow. 

Colorless  or 
white. 

Medium. 

Oxide  of  titanium. 

Grayish. 

Brownish- 
violet. 

Yellow. 

Nearly  color- 
less. 

Little. 

Oxides  of  iron  and 
uranium. 

Pale  green. 

Nearly  color- 
less. 

Yellow. 

Pale  yellow. 

Little. 

Oxide  of  cerium. 

Colorless. 

Colorless. 

Yellow. 

Yellowish- 
green. 

Little. 

Oxide  of  chromium. 

Green. 

Green. 

Yellow. 

Yellowish- 
green,  almost 
colorless. 

Little. 

Oxide  of  vanadium. 

Dirty 
green. 

Fine  green. 

Deep  yellow 
to  orange- 
red. 

Yellow. 

Medium 
to  much 

Oxide  of  cerium. 

Colorless. 

Colorless. 

Deep  yellow 
to  orange  - 
red. 

Yellow. 

Medium 
to  much 

Oxide  of  uranium. 

Pale  green. 

Pale  green  to 
nearly  col- 
orless. 

IMPORTANT   BLOWPIPE   AND   CHEMICAL   REACTIONS.  149 

TABLE   OF   REACTIONS   OBTAINED   WITH   BORAX. — Continued. 


Oxidizing  Flame. 

Amount 
of 
Material. 

Produced  by 

Reducing  Flame. 

Hot. 

Cold. 

Hot. 

Cold. 

Deep  yellow 
to  orange- 
red. 

Yellow. 

Medium 
to  much. 

Oxide  of  iron. 

Bottle- 
green. 

Pale     bottle- 
green. 

Deep  yellow 
to  orange- 
red. 

Yellowish- 
green. 

Medium 
to  much. 

Oxide  of  chromium. 

Green. 

Green. 

Green. 

Blue. 

Little  to 
medium. 

Oxide  of  copper. 

Colorless  to 
green. 

Opaque   red 
with  much 
oxide. 

Green. 

Yellow,    green, 
or  blue,  of  va- 
rious shades. 

Medium. 

Various  mixtures  of 
the  oxides  of  iron, 
copper,       nickel, 
and  cobalt. 

(?) 

(?) 

Blue. 

Blue. 

Little  to 
medium. 

Oxide  of  cobalt. 

Blue. 

Blue. 

Violet. 

Reddish-brown. 

Little  to 
medium. 

Oxide  of  nickel. 

Opaque 
gray. 

Opaque  gray. 

Violet. 

Reddish-violet. 

Little. 

Oxide  of  manganese. 

Colorless. 

Colorless. 

Pale  rose. 

Pale  rose. 

Much. 

Oxide  of  didymium. 

Pale  rose. 

Pale  rose. 

b.  Fusion  with  PHOSPHORUS  SALT  on  Platinum  Wire. 

TABLE   OF   REACTIONS    OBTAINED    WITH   PHOSPHORUS   SALT. 


Oxidizing  Flame. 

Amount 
of 

Reducing  Flame. 

Material. 

Produced  by 

Hot. 

Cold. 

Hot. 

Cold. 

Colorless. 

Colorless,    but 

Little  or 

Oxides    of  calcium 

Colorless. 

Colorless,    but 

when  strong- 

much. 

strontium,  barium, 

when  strong- 

ly   saturated 
the     beads 

magnesium,  berylli- 
um,   zinc,    alumin- 

ly   saturated 
the         beads 

may  in  some 

ium,    yttrium,  lan- 

may in  some 

cases   appear 

thanum,     thorium. 

cases   appear 

opaque  white. 

zirconium,  tin.  and 

opaque  white. 

silicon,    the    latter 

almost  insoluble. 

Continued. 


150 


IMPORTANT   BLOWPIPE   AND   CHEMICAL   REACTIONS. 


TABLE   OF   REACTIONS    OBTAINED   WITH   PHOSPHORUS   SALT. — Confd. 


Oxidizing  Flame. 

Amount 
of 
Material. 

Produced  by 

Reducing  Flame. 

Hot. 

Cold. 

Hot. 

Cold. 

Very  pale 
yellow. 

Colorless. 

Much. 

Oxides  of  tantalum 
and  cadmium. 

Very  pale 
yellow. 

Colorless. 

Very  pale 
yellow. 

Colorless. 

Much. 
Much. 

Oxides  of  lead,  anti- 
mony, and  bismuth. 

Gray. 

Gray. 

Very  pale 
yellow. 

Colorless. 

Oxide  of  niobium. 

Brown. 

Brown. 

Pale  yellow. 

Colorless. 

Medium. 

Oxide  of  tungsten. 

Dirty  blue. 

Fine  blue. 

Pale  yellow. 

Colorless. 

Little  to 
medium. 

Oxide  of  titanium. 

Yellow. 

Violet. 

Yellow. 

Colorless. 

Medium. 

Oxide  of  cerium. 

Colorless. 

Colorless. 

Yellow. 

Colorless. 

Little. 

Oxide  of  iron. 

Very  pale 
yellow- 
ish-green. 

Colorless. 

Yellow. 

Pale  greenish- 
yellow. 

Medium. 

Oxide  of  uranium. 

Pale  dirty 
green. 

Fine  green. 

Yellowish- 
green. 

Colorless. 

Medium. 

Oxide    of    molybde-jDirty 
num.                               green. 

Fine  green. 

Deep  yellow 
to    brown- 
ish-red. 

Yellow  to  al- 
most     color- 
less. 

Medium 
to  much. 

Oxide  of  iron. 

Red,    yel- 
low,      to 
yellow- 
ish-green. 

Almost   color- 
less   to   very 
pale  violet. 

Yellow       to 
deep  yellow. 

Yellow. 

- 

Little    to 
medium. 

Oxide  of  vanadium. 

Dirty 

green. 

Fine  green. 

Reddish     to 
brownish- 
red. 

Yellow  to  red- 
dish-yellow. 

Little    to 
medium. 

Oxide  of  nickel. 

Reddish  to 
brown- 
ish-red. 

Yellow  to  red- 
dish-yellow. 

Green. 

Rather      pale 
blue. 

Little. 

Oxide  of  copper. 

Pale     yel- 
lowish- 
green. 

Pale          blue, 
nearly  color- 
less ;  at  times 
ruby-  red. 

Dark  green. 

Blue. 

Medium. 

Oxide  of  copper.         Brownish- 
green. 

Opaque  red. 

Green. 

Yellow,  green, 
or     blue,    of 
various 
shades. 

Medium. 

Various  mixtures  of 
the  oxides  of  iron,i 
copper,  cobalt,  and 
nickel. 

o 

? 

IMPORTANT    BLOWPIPE   AND   CHEMICAL   REACTIONS.  151 

TABLE   OF   REACTIONS    OBTAINED   WITH   PHOSPHORUS   SALT. — ConVd. 


Oxidizing  Flame. 

Amount 
of 
Material. 

Produced  by 

Reducing  Flame. 

Hot. 

Cold 

Hot. 

Cold. 

Dirty  green. 

Fine  green. 

Little    to 
medium. 

Oxide  of  chromium. 

Dirty 

green. 

Fine  green. 

Blue. 

Blue. 

Little    to 
medium. 

Oxide  of  cobalt. 

Blue. 

Blue. 

Grayish- 
violet. 

Violet. 

Medium. 

Oxide  of  manganese. 

Colorless. 

Colorless. 

Pale  rose. 

Pale  rose. 

Much. 

Oxide  of  didymium. 

Pale  rose. 

Pale  rose. 

c.  Fusion  witli  SODIUM  CARBONATE  on  Platinum  Wire. 

If  heated  in  the  oxidizing  flame,  an  opaque  bead,  green  when 
hot,  blue  when  cold,  indicates  manganese.  The  color  disappears 
in  the  reducing  flame. 

A  yellow  bead  in  the  oxidizing  flame  indicates  chromium. 

A  clear  glass  can  be  made  by  fusing  with  a  sufficient  quantity 
of  silica. 

G.  TREATMENT  WITH  ACIDS,  AND  REACTIONS  WITH  THE  COMMON 

REAGENTS. 

As  a  general  rule,  it  may  be  recommended  to  treat  1  or  2  ivory 
spoonfuls  of  the  finely  powdered  mineral  in  a  test-tube  with  about 
5  cc.  of  acid ;  heat  to  boiling,  and  observe  any  changes  which  take 
place.  For  minerals  without  metallic  luster,  hydrochloric  acid  is 
usually  the  most  convenient  solvent,  while  for  the  sulphides  and 
arsenides,  which  usually  have  metallic  luster,  nitric  acid  is  best. 
The  following  should  be  especially  observed  : 

a.  Evolution  of  Gases. 

1.  CARBON  DIOXIDE,  C02. — Colorless  and  odorless.  Obtained 
from  all  carbonates  (p.  62,  §  1). 


152  IMPORTANT   BLOWPIPE   AND   CHEMICAL   REACTIONS. 

2.  HYDROGEN    SULPHIDE,   HaS. — Colorless,  with  disagreeable 
odor.     Obtained  from  sulphides  (p.  121,  §  7). 

3.  CHLORINE,    Cl. — Nearly  colorless,  with  disagreeable  odor. 
Obtained  from  a  few  higher  oxides  when  dissolved  in  hydrochloric 
acid  (p.  101,  §  2). 

4.  NITROGEN  DIOXIDE,  N0a.— Dark  red  vapors  derived  from 
nitric  acid  when  oxidation  is  taking  place  (p.  120,  §  6). 

b.  Color  of  the  Solution. 

A  great  variety  of  colors  may  be  obtained,  but  only  the  common  ones  will 
be  mentioned. 

1.  AMBER  TO  BROWNISH-RED. — Hydrochloric  acid  solutions 
containing  ferric  iron. 

2.  GREEN. — From  mixtures  of  copper  and  iron,  and  also  from 
nickel.    Addition  of  ammonia  in  excess  gives  a  blue  color  with  cop- 
per and  nickel,  the  former  being  more  intense. 

3.  BLUE. — From  copper,  and  greatly  intensified  by  adding  an 
excess  of  ammonia. 

4.  PINK  OR  PALE  ROSE. — From  cobalt. 

c.  Insoluble  Residue  after  Decomposing  a  Mineral. 

1.  A  JELLY. — When  this  is  obtained  by  evaporation  of  a  solu- 
tion, and  is  insoluble  upon  subsequent  addition  of  water  or  acid, 
it  indicates  a  silicate  (p.  108,  §  1). 

2.  A  PULVERULENT  RESIDUE. — White,  but  more  transparent 
in  the  acid  than  the  original  powdered  mineral ;  it  may  indicate 
a  silicate  (p.  109,  §  2). 

3.  WHITE  RESIDUES. — These  may  be  obtained  when  minerals 
containing  tin,  antimony,  and  sulphide  of  lead  are  oxidized  by 
nitric  acid. 

4.  A    YELLOW   RESIDUE.  —  This  may  indicate  tungsten.     A 
spongy  mass  or  fused  globule  of  sulphur  is  also  often  obtained 
when  sulphides  are  treated  with  nitric  acid  (p.  120,  §  6). 


IMPORTANT  BLOWPIPE   AND   CHEMICAL   REACTIONS.  153 

d.  Precipitation  by  Adding  Appropriate  Reagents  to  the  Clear 

Solution. 

Only  those  reagents  which  are  most  useful  in  making  simple  test-tube 
experiments  will  be  mentioned. 

1.  AMMONIA  precipitates  aluminium,  beryllium,  bismuth,  chro- 
mium (trivalent),  iron  (ferric),  lead,  and  the  rare  earth  metals 
(p.  65),  as  hydroxides. 

Under  a  variety  of  conditions,  especially  when  phosphoric,  arsenic,  si- 
licic, and  hydrofluoric  acids  are  present,  many  other  elements  may  be  precipi- 
tated ;  e.g.,  calcium  phosphate  is  precipitated  when  ammonia  is  added  to 
an  acid  solution  of  apatite  (p.  60,  §  4,  #). 

2.  AMMONIUM  CARBONATE  is  especially  convenient  for  precipi- 
tating calcium,  strontium,  and  barium  carbonates  from  solutions 
made  alkaline  by  ammonia. 

3.  AMMONIUM  Ox  A  LATE  is  useful  for  the  precipitation  of  cal- 
cium oxalate  from  solutions  made  alkaline  by  ammonia.     Barium 
and  strontium  are  also  precipitated. 

4.  AMMONIUM  SULPHIDE  precipitates,  from  solutions  which  are 
nearly  neutral   or  alkaline,   iron,    zinc,    manganese,   cobalt,  and 
nickel,  as  sulphides,  and  aluminium,  chromium,  and  the  rare  earth 
metals,  as  hydroxides.    It  is  also  useful  for  dissolving  freshly  pre- 
cipitated sulphides  of  arsenic,  antimony,  and  tin. 

5.  BARIUM  CHLORIDE  precipitates  barium  sulphate  from  acid 
solutions,  and  serves,  therefore,  as  a  very  delicate  test  for  a  sul- 
phate. 

6.  HYDROCHLORIC  ACID  precipitates  silver,  lead,  and  mercu- 
rous  chlorides  from  nitric  acid  solutions. 

7.  HYDROGEN  SULPHIDE  gas,  when  led  into  hydrochloric  or 
sulphuric  acid  solutions,  precipitates  silver,  lead,  mercury,  copper, 
bismuth,  cadmium,  arsenic,  antimony,  and  tin,  as  sulphides.     If 
the  solution  is  in  nitric  acid,  it  is  best  to  evaporate  in  a  casserole 
with  sulphuric  acid,  until  the  nitric  acid  is  expelled,  and  then, 
after  dissolving  in  water,  to  run  in  the  hydrogen  sulphide  gas. 


154  IMPORTANT   BLOWPIPE   AND   CHEMICAL   REACTIONS. 

8.  SILVER  NITRATE  precipitates  silver  chloride,  bromide,  or 
iodide  from  solutions  of  chlorides,  bromides,  or  iodides,  in  water  or 
dilute  nitric  acid. 

9.  SODIUM  CARBONATE  precipitates  iron,  zinc,  manganese,  co- 
bait,  nickel,  copper,  magnesium,  and  many  other  metals,  as  basic 
or  normal  carbonates. 

10.  SODIUM  HYDROXIDE  precipitates  iron,  manganese,  cobalt, 
nickel,  copper,  bismuth,  cadmium,  magnesium,  and  the  rare  earth 
metals,  as  hydroxides,  some  of  these  only  in  the  absence  of  ammo- 
nium salts. 

11.  SODIUM  PHOSPHATE  is  useful  for  detecting  magnesium  in 
solutions  which  are  not  precipitated  by  ammonia  and  ammonium 
carbonate,  or  have  been  filtered  from  the  precipitates  produced  by 
these  reagents. 

12..  SULPHURIC  ACID  precipitates  lead,  barium,  strontium,  and 
calcium  sulphates,  the  last,  however,  only  when  the  solutions  are 
concentrated. 


CHAPTER  Y. 

PHYSICAL  PROPERTIES  OF  MINERALS. 

IN  the  foregoing  chapters,  minerals  have  been  regarded  from 
the  standpoint  of  their  chemical  composition  only,  but  they  pos- 
sess in  addition  certain  pliysical  properties  which  may  be  very 
useful  for  their  identification  and  recognition.  The  most  im- 
portant of  these  are  crystallization,  luster,  color,  hardness,  fusi- 
bility, and  specific  gravity. 

CRYSTALLOGRAPHY.* 

Crystallization.  —  When  a  mineral  or  chemical  compound 
assumes  a  solid  form,  it  does  so  by  separation  from  a  solution,  or 
from  a  molten  mass,  or  by  condensation  from  a  vapor ;  and  the 
molecules,  or  smallest  particles  of  the  substance,  generally  assume 
a  definite  arrangement.  This  process  is  called  crystallization,  and 
when  it  takes  place  under  favorable  circumstances  it  gives  rise  to 
crystals,  or  solids  which  have  not  only  definite  internal  struc- 
ture or  arrangement  of  the  molecules,  but  also  definite  shapes 
bounded  by  flat  surfaces. 

Yery  little  is  known  concerning  the  molecules  which  form  crys- 
tals :  they  may  correspond  to  the  chemical  molecules,  but  are 
probably  larger,  and  aggregates  of  them  ;  and  certainly  in  all  in- 
stances they  are  excessively  minute.  It  is  a  very  important  prop- 
erty of  crystals  that,  during  their  growth,  the  molecules  of  the 
substance  tend  to  arrange  or  group  about  themselves  only  those  of 

*  Owing  to  limited  space,  this  important  subject  will  Lave  to  be  treated  in  a  somewhat 
elementary  manner,  but  it  is  hoped  that  the  essential  features  can  be  presented  with  suf- 
ficient clearness  to  enable  the  student  to  become  familiar  with  the  more  important,  sim- 
ple, crystalline  forms  and  combinations.  To  obtain  a  really  satisfactory  knowledge  of  the 
subject  it  is  quite  essential  to  supplement  the  text  by  a  collection  of  crystals  or  models. 

155 


156  CRYSTALLIZATION". 

the  same  Tcind.  The  crystallized  condition  of  a  compound  is,  there- 
fore, one  of  the  very  best  proofs  of  its  homogeneous  character  and 
purify. 

That  solids  with  plane  surfaces  may  result  from  the  arrange- 
ment of  particles  of  the  same  kind  is  shown  by  Fig.  50,  which  rep- 


FIG.  50. 

Cube,  octahedron,  and  dodecahedron  made  by  the  regular  arrangement  of  shot.  The  arrangement 
of  the  shot  is  identical  in  the  three  models,  but  different  layers  of  shot  constitute  the  outer  or  limiting 
surfaces. 

resents  geometrical  shapes  made  by  a  regular  arrangement  of  shot. 
If  the  shot  were  so  exceedingly  small  that  the  individual  ones 
could  not  be  seen,  the  outer  surfaces  of  the  solids  would  appear 
perfectly  smooth  and  flat.  Such  an  arrangement  is,  however,  some- 
what misleading,  since  the  shot  are  in  contact  with  one  another, 
while  in  crystals  the  distances  between  the  molecules  are  probably 
considerably  greater  than  the  diameters  of  the  molecules  them- 
selves. A  more  correct  idea,  therefore,  of  an  arrangement  of  mole- 
cules in  a  crystal  may  be  gained  from  Fig.  51.  In  a  crystal  the 
molecules  are  all  of  the  same  kind,  and  in  any  given  direction  they 
must  be  equally  distant  from  one  another. 

As  in  an  orchard  where  the  trees  are  evenly  spaced  one  may 
look  in  different  directions,  a&,  a<?,  af,  etc.,  (Fig.  52),  and  seethe 
trees  in  rows,  so  through  a  regular  arrangement  of  particles,  as  in 
Fig.  51,  there  are  certain  definite  directions  in  which  the  particles 
lie  in  planes.  The  crystal  faces  correspond  to  molecular  planes, 
and  have  definite  inclinations  or  angles,  depending  upon  the  mo- 
lecular arrangement. 

Provided  a  crystal  has  not  been  hindered  in  its  development  it 
will  be  bounded  by  flat  surfaces,  which  give  it  a  regular  external 


CRYSTALLIZATION. 


157 


form,  and  this  is  one  of  its  most  striking  features.  It  is  only  occa- 
sionally, however,  that  a  crystal  develops  without  interruption,  for 
it  usually  is  interfered  with  by  others,  or  grows  against  some  ob- 
stacle so  that  only  a  portion  or  perhaps  nothing  of  its  characteris- 
tic external  form  is  produced.  Even  when  the  external  form  is 
wholly  wanting,  the  crystalline  nature  of  a  substance,  due  to  the 
regular  arrangement  of  the  molecules,  may  be  revealed  by  some 
of  the  physical  properties  peculiar  to  crystals.  Thus  by  the  aid 


3 


-!-;*- 

44- 


\ 


»-6 


FIG.  51.  FIG.  52. 

of  polarized  light  it  could  instantly  be  told  that  a  transparent  frag- 
ment of  quartz  possessed  a  crystalline  structure  and  was  not  a  bit 
of  glass. 

Most  minerals  have  been  observed  in  a  crystallized  condition, 
and  it  is  important  to  bear  in  mind  that  only  definite  chemical 
compounds  possess  this  peculiar  property  of  crystallization. 

Constancy  of  the  Interfacial  Angles  of  Crystals.  —  One  of 
the  most  important  features  of  crystals  is  that  those  of  the  same 
substance  invariably  exhibit  the  same  angles  between  similar 
faces.  It  is  evident  that  in  an  orchard  one  must  look  in  definite 
directions,  ab,  of,  ag,  etc.  (Fig.  52),  to  see  the  trees  in  rows, 
these  directions  depending  upon  the  way  in  which  the  trees  are 
planted.  In  Fig.  52  the  trees  are  represented  as  equally  spaced 
along  the  rows  ab  and  ag,  with  these  rows  at  right  angles  to  one 
another.  It  must  also  follow  that  constancy  of  interfacial  angles 
is  a  feature  of  crystals,  provided  each  substance  has  its  own  defi* 


158 


GONIOMETERS. 


nite  molecular  structure  (Fig.  51),  and  that  the  faces  correspond  to 
layers  of  molecules. 

Goniometers. — Instruments  for  measuring  the  interfacial  an- 
gles of  crystals  are  called  goniometers. 

The  reflection  goniometer  consists  of  a  divided  circle  turning 
upon  an  axis,  and  provided  with  devices 
for  holding  and  adjusting  crystals  so  that 
the  edge  between  the  faces  to  be  measured 
can  be  made  to  coincide  with,  and  be 
paralled  to,  the  axis  of  the  instrument. 
Rays  of  light  I  (Fig.  53),  either  coming  from 
a  distant  object,  or  made  parallel  by  pass- 
ing through  a  lens,  fall  upon  the  face  ac 
of  a  crystal,  and  some  of  them  are  reflected 

in  the  direction  of  the  observer  ce.  It  is  evident  that  in  order  to 
obtain  a  reflection  in  a  similar  direction  from  the  face  c&,  it  will  be 
necessary  to  turn  the  crystal  through  the  angle  /?,  which  is  the 
supplement  of  the  angle  ac5,  the  angles  being  read  from  a  divided 
circle.  Measurements  can  thus  be  made  with  great  accuracy  even 
on  very  small  crystals.  In  studying  and  calculating  the  mathe- 
matical relations  of  crystal  faces,  the  supplement  angles  are  much 
more  convenient  to  use  than  the  actual  ones,  and  are  almost  in- 
variably  employed  by  crystallographers. 

An  inexpensive  contact  goniometer,  designed  by  the  author, 
consists  of  a  graduated  semicircle 
(Fig.  54)  printed  on  cardboard,  and 
provided  with  a  measuring  arm 
of  transparent  celluloid  which  is 
swiveled  by  means  of  an  eyelet 
exactly  in  the  center  of  the  arc. 
A  fine  line,  scratched  on  the  under 
surface  of  the  celluloid  arm  and 
blackened,  and  in  exact  alinement 
with  the  center  of  the  eyelet,  serves  FIG.  54.  (About  £  natural  size). 
to  indicate  the  angle.  In  using  the  instrument  the  edges  of  the 


CRYSTALLOGKAPHIC    AXES. 


159 


card  and  measuring  arm  are  brought  as  nearly  as  possible  in  con- 
tact with  the  crystal  faces,  care  being  taken  that  the  plane  of  the 
card  is  held  at  right  angles  to  the  edge  formed  by  the  intersection 
of  the  crystal  faces. 

Crystallographic  Axes. —  In  order  to  show  the  relations  of 
crystal  faces  it  is  convenient  to  take  certain  directions  within  the. 
crystals  as  axes.  Usually  three  are  chosen  (Fig.  55),  one  a  -a, 
going  from  front  to  back,  another  b  -b,  from  right  to  left,  and  a 
third  c  -<?,  vertical.  Positive  ^  negative  directions  are  assumed 
from  the  center,  as  indicated  m  me  figure.  Crystal  faces  intersect 
these  axes,  and,  by  measuring  appropriate  interfacial  angles,  the  re- 
lative  lengths  of  the  axes,  or  their  ratio  to  one  another,  can  be  de- 
termined. For  example,  sulphur  crystals  have  the  form  of  a  pyra- 


+  c 


-c 
FIG.  55. 


FIG.  56. 


FIG.  57. 


mid  (Fig.  56),  and  the  angles  which  are  measured  over  the  edges 
joining  the  a  and  &,  and  the  b  and  c  axes,  respectively,  equal  36° 
40?'  and  94°  52'.  From  these  angles  it  can  be  calculated,  by  simple 
mathematical  processes,  that,  if  the  length  ob  is  assumed  as  unity ^ 
the  lengths  oa  and  oc  are  0.813  and  1.903,  respectively.  Designat- 
ing the  lengths  of  the  axes  oa,  ob,  and  oc  as  a,  &,  and  c,  the  fore- 
going mathematical  relation  can  be  expressed  as  follows :  a :  b  :  c 
=  0.813  : 1 : 1.903.  This  is  known  as  the  axial  ratio  of  sulphur. 

When  the  axes  are  not  at  right  angles  to  one  another  the  an- 
gles or,  /?,  and  y  (Fig.  57)  must  be  determined. 


160  PARAMETERS. 

Parameters. — Parameters  are  the  distances  from  the  center  o 
(Fig.  56),  at  which  crystal  faces  intersect  the  axes.  For  example, 
oa,  ob,  and  oc  are  the  parameters  of  the  face  abc.  If  oa,  ob,  and  oc 
correspond  to  the  characteristic  lengths  of  the  respective  axes  of 
any  mineral,  the  face  in  question  is  then  said  to  have  the  param- 
eters a  :  b  :  c. 

It  must  be  distinctly  borne  in  mind  that  the  parameter  dis- 
tances oa,  ob,  and  oc,  or  the  axial  lengths,  are  not  expressed  in 
terms  of  any  unit  of  measure,  but  have  only  relative  values.  For 
example,  no  matter  what  length  is  chosen  for  the  b  axis,  if  a  and 
c  have  relatively  the  lengths  that  have  been  determined  for  sul- 
phur, a  :  b  :  c  =  0.813  : 1 :  1.903,  then  the  eight  plane  surfaces  which 
intersect  the  extremities  of  the  a,  b,  and  c  axes  will  form  a  pyra- 
mid (Fig.  56)  whose  interfacial  angles  will  be  like  those  of  a  sul- 
phur crystal. 

Law  of  Definite  Mathematical  Ratio, — It  is  a  very  impor- 
tant feature  of  crystals  that  their  faces,  prolonged  if  necessary, 
will  intersect  the  axes  only  at  the  ratio  distances  a,  b,  and  c, 
characteristic  of  each  substance,  or  at  simple  multiples,  or  frac- 
tions, of  these  ratio  distances.  A  plane  may,  however,  be  parallel  to 
one  or  two  of  the  axes,  which  is  indicated  by  the  sign  of  infinity. 
Given  the  axes  a  -a,  b  -b,  and  c  -c  (Fig.  58)  of  the  ratio  lengths 
characteristic  for  any  substance,  then  possible 
crystal  faces  might  have  the  parameter  relations 
a  :  b  :  c,  2a:b  \  c,  a  :  b  :  %c,  etc. ,  or  oo  a  :  b  :  c, 
oo  a  :  oo  b  :  c,  etc.  Experience  has  shown,  more- 
over, that  the  multiples  at  which  the  character  is- 
tic  axial  lengths  are  cut,  are  most  often  unity 
(not  expressed  before  the  letters)  and  infinity,  or 
such  simple  quantities  as  2,  3,  J,  or  £.  When  no 
sign  is  expressed,  a  positive  one  is  always  under- 
stood. 

As  a  further  illustration  of  this  very  impor- 
tant principle,  suppose  three  wires  are  fastened  together  at  right 
angles  to  one  another,  and  cut  off  so  that  their  relative  lengths 


INDICES. 


161 


FIG.  59. 


FIG.  60. 


shall  correspond  to  the  crystallographic  axes  of  sulphur,  a:b:c 
—  0.813  : 1 :  1.903  (Fig.  59),  then  the  eight  planes  joining  the  ex- 
tremities of  the  a,  b,  and  c  axes,  and  another  set  of  eight  planes 
going  from  the  extremities  of  the  a  and  b  axes  to  i  on  the  c  axis, 
would  have  the  direction,  or  make 
with  one  another,  the  character- 
istic angles  of  the  faces  p  and  s 
(Fig.  60)  which  occur  on  crystals 
of  sulphur.  It  will  be  observed 
from  a  consideration  of  Figs.  59 
and  60  that  the  faces  p,  having 
their  origin  at  a  and  b,  do  not  in- 
tersect the  vertical  axis,  but,  if 
extended,  would  do  so  at  c.  Also, 
the  faces  s,  having  their  origin  at 
a  certain  distance  on  the  vertical  axis,  when  extended  would 
intersect  the  horizontal  axes  at  points  beyond  a  and  b.  The 
relative  distances,  however,  at  which  the  three  axes  are  cut  by 
the  s  faces  are  the  same  as  those  of  the  planes  indicated  by 
dotted  lines  in  Fig.  59,  going  from  a  :  b  :  %c,  for  the  s  faces  are  paral- 
lel to  these. 

It  must  be  distinctly  borne  in  mind  that  parameter  relations 
furnish  a  means  of  expressing  the  directions  of  crystal  faces 
when  they  are  referred  to  axes  of  known  lengths  and  position, 
but  they  in  no  way  affect  the  size  of  the  faces.  A  crystal  face 
may  be  regarded  as  shifted  to  any  extent,  provided  it  is  kept 
parallel  to  its  original  position,  without  in  the  least  affecting  the 
relative  distances  at  which  the  axes  are  intersected. 

Indices.— The  position  and  direction  of  crystal  faces  with 
reference  to  axes  can  also  be  expressed  by  numbers,  known  as 
indices,  which  are  the  reciprocals  of  the  parameters.  The  recip- 
rocal of  a  number  is  one  divided  by  the  number,  4  =  0.  In- 
dices are  written  as  whole  numbers,  the  reciprocal  values  being 
cleared  of  fractions  when  necessary,  and  the  minus  sign,  when 
needed,  is  written  over  the  number. 


162 


SYMMETRY. 


The  following  examples  will  serve  to  illustrate  the  relations  of 
parameters  and  indices : 


Parameters. 

a  :  b  :  c 
a  :b  :  coc 
oca  :  oo&  :  —  c 


Indices. 
Ill 

110 

001 


Parameters. 

2a  :  b  :  c 

a  :  —  f  1}  :  3c 
—a  :  b  :    c 


Indices. 

122 
321 

113 


If  one  will  keep  in  mind  the  reciprocal  relation  existing  be- 
tween  indices  and  parameters ,  it  soon  becomes  an  easy  matter 
to  use  indices,  and  to  conceive  of  the  position  and  direction  of 
crystal  faces  expressed  by  them.  For  example,  001  designates  a 
plane  parallel  to  the  a  and  b  axes,  and  intersecting  the  negative 
end  of  c.  The  indices  122  (read  one,  two,  two)  designate  a  face 
intersecting  a,  %b,  and  \c  ;  such  a  plane  is  parallel  to,  and,  there- 
fore, crystallographically  identical  with,  a  plane  expressed  by  the 

parameter  relation  2a  :  b  :  c 
(Fig.  61).  The  indices  321 
designate  a  face  intersect- 
ing Ja,  —  %b,  and  c,  which 
is  parallel  to  the  face  hav- 
ing the  parameter  relation 
a  :  -  f  ft  :  3c  (Fig.  62). 

FIG.  61.  FIG.  62.  It  is  important  to  note 

the  order  in  which  the  indices  are  written,  the  first,  second,  and 
third  numbers  referring  invariably  to  the  characteristic  a,  b,  and 
c  axes. 

Since  indices  furnish  a  very  convenient  method  of  expressing 
crystallographic  relations,  they  have  been  almost  universally 
adopted  by  crystallographers. 

Symmetry. — Upon  examining  crystals  it  will  be  observed  that 
there  is  a  certain  regularity  in  the  recurrence  of  faces  and  angles 
of  the  same  kind,  which  is  designated  as  symmetry.  The  sym- 
metry of  crystals  is  expressed  in  terms  of  imaginary  planes  and 
axes  passing  through  them. 


THE    CRYSTAL    FORM.  163 

Symmetry  Plane.  —  A  plane  is  called  a  symmetry  plane  when  it 
divides  a  crystal  in  such  a  manner  that  the  faces 
and  angles  on  one  side  of  the  plane  are  repeated 
on  the  side  directly  opposite.  Thus  in  Fig.  63  of 
orthoclase,  the  shaded  plane  divides  the  figure 
symmetrically.  A  symmetry  plane  is  of  such  a 
nature  that,  if  a  crystal  is  held  before  a  mirror 
with  the  symmetry  plane  parallel  to  the  reflecting 
surface,  the  crystal  and  its  reflection  present  the 
same  appearance. 

Symmetry  Axis.  —  When  a  crystal,  on  being  revolved,  shows  a 
recurrence  of  similar  faces  and  angles,  the  direction  about  which 
the  revolution  has  taken  place  is  called  an  axis  of  symmetry. 
In  Fig.  63  the  direction  at  right  angles  to  the  face  b  is  an  axis 
of  symmetry  ;  by  a  turning  of  180°  about  this  axis,  the  crystal 
would  occupy  the  same  position  in  space,  and  therefore  present 
the  same  appearance.  The  symmetry  of  crystals  as  referred  to 
axes  is  of  four  kinds  :  binary,  trigonal,  tetragonal,  and  liexa- 
gonal,  according  as  the  recurrence  of  similar  parts  or  features 
takes  place  two,  three,  four,  or  six  times  during  a  revolution  of 
360°,  and  the  four  kinds  are  indicated  by  the  following  signs: 


Crystallographic  axes,  (page  159)  correspond  to  axes  of  sym- 
metry whenever  it  is  possible  to  make  them. 

Center  of  Symmetry.  —  A  crystal  is  said  to  have  a  center  of 
symmetry  when  it  is  so  developed  that  for  every  face  there  is  a 
possible  one  of  exactly  similar  character,  diametrically  disposed 
with  reference  to  a  central  point. 

The  Crystal  Form.  —  All  of  the  faces  of  the  same  kind  which 
are  possible  on  a  crystal  of  given  symmetry  constitute  a  crystal 
form.  For  example,  take  the  axes  of  binary  symmetry,  a  -a, 
b  -b,  and  c  -c  (Fig.  64),  which  are  of  unequal  lengths  and  at 
right  angles  to  one  another,  and  assume  that  there  are  three 
planes  of  symmetry,  each  passing  through  two  of  the  axes  ;  the 
eight  faces  intercepting  the  extremities  of  the  axes  would  then 


164 


THE   CRYSTAL   FORM. 


be  alike  and  would  produce  a  form  known  as  a  pyramid.  In 
giving  the  symbol  of  such  a  form  it  is  custom- 
ary to  give  the  parameters  a  :  b  :  c,  or  indices 
(111)  of  only  one  of  the  faces,  since  the  number 
of  possible  faces  of  the  same  kind  can  readily 
be  told,  provided  the  symmetry  is  'known. 

In  Fig.  63,  which  represents  an  orthoclase 
crystal  with  one  axis  of  binary  symmetry  and 
one  plane  of  symmetry,  there  are  three  forms, 
b,  c,  and  y,  each  consisting  of  two  faces,  and 
a  fourth  form  m,  having  four  faces. 

Normal  or  Holohedral  Forms. — Fig.  64  rep- 
resents the  most  symmetrical  arrangement  of  the  crystal  faces 
about  the  axes  a  -a,  b  -b,  and  c  -c.  Eight  faces  of  the  same 
kind  are  possible,  all  of  which  are  developed,  and  the  term 
normal  form  will  be  used  for  designating  crystals  of  this  charac- 
ter. It  is  also  customary  to  designate  such  a  form  as  TioloTiedral 
(oAo^  whole,  and  edpa,  face). 

Hemihedrism. — About  a  system  of  three,  unequal  axes,  at  right 
angles  to  one  another,  it  is  possible  to  have 
forms  with  a  lower  degree  of  symmetry  than 
that  of  the  pyramid  (Fig.  64).  For  example, 
provided  the  axes  are  symmetry  axes,  and  that 
there  are  no  planes  of  symmetry,  the  form  - 
a:b:c  (111)  would  then  consist  of  four  faces 
(Fig.  65).  Such  a  form  is  often  designated  as 
Jiemihedral  (?//^,  half,  and  edpa,  face),  since  it  has 
only  half  as  many  faces  as  are  possible  when 
the  highest  degree  of  symmetry  prevails. 

Hemimorphism. — This  term  is  applied  to  the  property,  exhib- 
ited by  some  minerals,  of  having  different  crystalline  forms  at 
opposite  extremities  of  an  axis  of  symmetry.  Thus,  a  crystal  of 
calamine  (Fig.  66)  shows  the  forms  lettered  c,  t,  and  i  above,  which 
are  different  from  v  below.  Crystals  of  tourmaline  (Figs.  67  and 
68)  have  very  different  forms  at  the  upper  and  lower  extremities 


FIG.  65. 


CKYSTAL    HABIT. 


165 


of  the  vertical  axis.      Hemimorpliic  crystals  show  marked  pyro- 
electricity,  see  p.  231. 


FIG.  66.  FIG.  67. 

Crystal  Habit. — It  is  characteristic  of  every  substance  that 
its  crystals  possess  a  certain  kind  of  symmetry,  or  belong  to  a  cer- 
tain system  of  crystallization,  although  their  forms  or  habit  may 
be  very  different.  Thus  Figs.  69,  70,  and  71  illustrate  the  forms 


FIG.  69. 


FIG.  70. 


FIG.  71. 


of  the  cube,  octahedron,  and  dodecahedron,  which  may  be  observed 
in  fluorite.  The  shot  models  (Fig.  50,  p.  156)  also  show  these  three 
forms,  and  will  perhaps  serve  to  explain  why  it  is  that  there  can 
be  a  difference  in  habit.  The  forms  of  the  models  depend  upon 
the  directions  of  the  layers  of  shot  which  represent  the  outer  or 
limiting  surfaces,  while  the  arrangement  of  the  shot  with  reference 
to  one  another  is  the  same  in  all  three  models.  As  explained 
on  p.  155,  each  chemical  substance  possesses  a  definite  arrangement 
of  its  crystal  molecules,  but  layers  of  molecules  having  different 
directions  may  constitute  the  crystal  faces. 

Distorted  Crystals. — It  generally  happens  that  during  the 
growth  of  crystals  material  is  supplied  more  abundantly  to  some 
parts  than  to  others,  and  consequently  they  do  not  attain  an  ideally 


166 


CRYSTAL   COMBINATIONS. 


symmetrical  development.  For  example,  although,  pyrite  crystal- 
lizes in  cubes  (Fig.  72),  it  is  frequently  found  in  forms  having  some 
faces  larger  than  others  (Figs.  73  and  74).  These  forms,  although 
departing  from  the  type  of  a  geometrical  cube,  are  considered,  crys- 


i_ 


FIG.  72. 


FIG.  73. 


FIG.  74. 


tallographically,  as  distorted  cubes,  since  each  interfacial  angle 
equals  90°,  and  all  the  faces  have  similar  physical  properties. 
Fig.  75  represents  a  symmetrical  octahedron  and  Fig.  76,  a  dis- 
torted one  ;  Fig.  77,  a  symmetrically  developed  quartz  crystal,  and 
Fig.  78,  a  distorted  one  with  the  corresponding  faces  m,  r,  and  2 
differently  developed. 


FIG.  75. 


FIG.  76. 


FIG.  77. 


FIG.  78. 


Distorted  crystals  are  the  rule  rather  than  the  exception,  al- 
though the  distortion  is  not  usually  so  great  as  represented  by  the 
foregoing  illustrations.  Moreover,  it  should  be  clearly  understood 
that  the  characteristic  interfacial  angles  of  crystals  are  in  no  way 
affected  by  inequalities  in  the  size  of  similar  faces. 

Crystal  Combinations. — The  occurrence  of  two  or  more  dif- 
ferent forms,  or  dissimilar  kinds  of  faces,  on  a  single  crystal  is 
called  a  combination.  Fig.  60  (p.  161)  illustrates  the  way  the  forms 
p  and  s  combine  on  a  crystal  of  sulphur,  and  Fig.  63  (p.  163),  a  com- 


TWIN  CRYSTALS. 


167 


FIG.  79. 


bination  of  the  four  forms  &,  c,  y,  and  m  on  a  crystal  of  orthoclase. 
Farther  on,  when  the  systems  of  crystallization  are  described,  this 
important  subject  of  crystal  combinations  will  be  more  fully  illus- 
trated and  explained. 

Truncations. — When  an  edge  which  would  be  formed  by  the 
meeting  of  two  crystal  faces  is  replaced  by  a  plane,  that  edge  is 
said  to  be  truncated.  Fig.  79  represents  a  cube  a 
whose  edges  are  truncated  by  the  planes  d.  The 
term  truncation  is  generally  used  in  a  restricted 
sense,  to  denote  that  truncating  planes  make  equal 
angles  with  the  adjacent  faces.  When  the  angles 
on  adjacent  faces  are  unequal  the  term  oblique 
truncation  is  used. 

A  solid  angle  is  said  to  be  truncated  when  it  is 
replaced  by  a  plane.  Fig.  80  represents  a  cube  a 
whose  solid  angles  are  truncated  by  the  planes  o.  FlG-  80- 

Twin  Crystals. — When  crystals  grow  together  in  other  than  a 
parallel  position,  so  that  they  have  a  certain  crystallograpTiic 
plane,  or  direction,  in  common,  they  are  known  as  twin  crystals. 
These  generally  present  the  appearance  of  two  halves  of  a  crystal 
(Fig.  81)  united  by  a  plane  called  the  twinning-plane,  and  are 
known  as  contact  twins.  Twin  crystals  of  this  type  are  of  such  a 


81. 


FIG.  82. 


FIG.  83. 


nature  that  die  lorm  of  a  simple  crystal  would  result  if  the  twins 
were  cut  in  two  along  the  twinning-plane,  and  either  one  of  the 
halves  should  be  revolved  180°  about  an  axis  which  is  at  right 
angles  to  the  twinning-plane.  Sucli  an  axis  is  known  as  the  twin- 
ning-axis.  For  example,  if  the  lower  half  of  the  twin  crystal  rep- 


168 


TWIN    CRYSTALS. 


resented  in  Fig.  81  was  thus  revolved,  an  octahedron  (Fig.  82)  would 
result ;  hence  such  a  crystal  is  called  a  twinned  octahedron. 

Two  individuals  may  also  appear  as  penetrating  through  one 
another  (Fig.  83)  and  such  are  known  as  penetration  twins.  In 
this  type  of  twins  one  of  the  individuals  is  brought  into  the  same 
position  as  the  other  by  a  revolution  of  180°  about  the  twinning- 
axis.  For  example,  the  cube  a  if  thus  revolved  about  the  twin- 
ning-axis  1 1  would  assume  the  position  of  the  cube  a. 

A  twinning-plane  can  never  be  a  symmetry-plane,  and  is  almost 
invariably  parallel  to  a  face  having  a  simple  relation  to  the  crys- 
tallographic  axes. 

Fig.  84  represents  a  simple  crystal  of  aragonite ;  Fig.  85,  a 
twin  in  which  one  of  the  m  faces  is  the  twinning-plane  ;  and 
Fig.  86,  a  repeated  twinning,  in  which  the  parts  I  and  III  are  in 
a  parallel  position,  and  have  between  them  a  lamella  II  in  twin 
position.  When  there  are  a  series  of  lamellae  in  twin  position  the 
twinning  is  said  to  be  poly  synthetic.  Fig.  87  represents  a  piece  of 


*z& 


Om 


FIG.  84. 


FIG.  85. 


FIG.  86. 


FIG.  87. 


oligoclase  feldspar  where  the  polysynthetic  twinning  has  given 
rise  to  a  surface  which  appears  distinctly  striated,  and  consists 
of  a  series  of  alternating  re-entrant  and  salient  angles.  Fig.  88 
represents  a  twin  grouping  of  rutile  prisms  which  cross  one  an- 
other at  angles  of  about  60°  and  120°;  and  Fig.  89,  a  repeated 
twinning  of  rutile  where  eight  individuals  unite  to  form  a  rosette. 
Twinning  often  gives  rise  to  very  complex  forms. 


THE   SYSTEMS   OF   CRYSTALLIZATION. 


169 


Although  re-entrant  angles  are  a  prominent  feature  of  twin  crys- 
tals, they  are  not  to  be  taken  as  a  necessary  indication  of  twinning. 
Crystals  grow  together  in  parallel  and  all  possible  accidental  posi- 


FlG. 


FIG.  89. 


FIG.  90. 


tions,  giving  rise  occasionally  to  groupings  with  re-entrant  angles 
which  may  closely  resemble  twin  crystals,  but  are  entirely  distinct 
from  them.  Fig.  90  represents  a  parallel  growth  of  octahedrons  of 
magnetite. 

The  Systems  of  Crystallization. — Although  there  is  an  almost 
unlimited  variety  in  the  forms  of  crystals,  they  can  all  be  classified 
under  the  following  six  divisions,  or  systems  of  crystallization : 
I.  Isometric.  III.  Hexagonal.  V.  MonocKnic. 

II.  Tetragonal.  IV.  Orthorhombic.      VI.  Triclinic. 

The  character  of  the  different  systems,  and  the  prominent  forms 
which  they  present,  will  be  described  on  subsequent  pages. 


ISOMETRIC   SYSTEM. 

The  forms  in  this  system  can  be  referred 
to  three  axes,  whicJi  are  at  right  angles  to 
one  another  and  of  equal  lengths  (Fig.  91). 
Since  the  axes  are  alike,  they  are  all  desig- 
nated by  the  symbol  a,  but  in  referring 
crystal  faces  to  them  a  definite  order  is 
adopted,  as  a, ,  a, ,  and  as. 


-a2 


a  3 


-a  3 
FIG.  91. 


forms  of  the  Normal  Group.— Galena- Type. 

All  the  forms  and  combinations  of  this  group  are  characterized 
by  having  three  axes  of  tetragonal,  four  of  trigonal,  and  six  of 


170 


ISOMETRIC   SYSTEM. 


binary  symmetry  (Fig.  92)  ;    also  by  having  three  axial  and  six 
diagonal  planes  of  symmetry  (Figs.  93  and  94). 


FIG.  92.  FIG.  93.  FIG.  94. 

Cube. — The  cube  a  (Fig.  95)  has  six  square  faces,  each  of 
which  intersects  one  axis  and  is  parallel  to  the  other  two.  The 
symbol  is  (100).  The  interfacial  angles  are  90°.  The  faces  are  all 
alike.  This  is  also  true  of  the  eight  solid  angles  and  twelve  edges. 
(Compare  distorted  cubes,  p.  166.)  Galena,  fluorite,  and  halite 
commonly  crystallize  in  cubes. 

Octahedron. — The  octahedron  o  (Fig.  96)  has  eight  faces,  each 
of  which  intersects  the  three  axes  at  equal  distances  from  the  cen- 
ter. The  symbol  is  (111).  The  faces  are  equilateral  triangles  and 
the  interfacial  angles  are  70°  32'.  The  faces  are  alike,  as  are  also 
the  six  solid  angles  and  the  twelve  edges.  (Compare  distorted 
octahedrons,  p.  166.)  Galena,  magnetite,  and  fluorite  often  crystal- 
lize in  octahedrons. 


FIG.  95.  FIG.  96.  FIG.  97. 

Dodecahedron. — The  dodecahedron  d  (Fig.  97)  called  often  the 
rhombic  dodecahedron,  has  twelve  rJiombic  faces,  each  of  which 
intersects  two  of  the  axes  at  the  same  distance  and  is  parallel  to 
the  third.  The  symbol  is  (110).  The  interfacial  angles  are  60°. 
The  faces  are  alike,  and  so  also  are  the  twenty-four  edges,  but  the 


NORMAL    GROUP. 


171 


solid  angles  are  of  two  kinds,  namely  :  those  at  the  extremities  of 
the  axes,  made  by  the  meeting  of  four  faces,  and  those  at  the  cen- 
ters of  the  octants,  made  by  the  meeting  of  three  faces.  Garnet 
and  magnetite  occur  in  dodecahedrons. 

Crystals  which  show  the  combination  of  the  cube  a,  the  octa- 
hedron o,  and  the  dodecahedron  <#,  as  illustrated  by  Figs.  98  to  104, 
will  often  be  found.  None  of  these  combined  forms  receive  a  spe- 
cial name,  but  can  be  designated  as  follows :  Fig.  98,  a  combina- 


FIG.  98.  FIG.  99.  FIG.  100.  ;  ( ,.,    FIG.  101. 

lion  of  cube  and  octahedron ;   Fig.  102,  a  combination  of  octa- 
hedron and  dodecahedron  ;  Fig.  104,  a  combination  of  cube,  do- 


FIG.  102. 


FIG.  103. 


FIG.  104. 


decahedron,  and  octahedron,  etc.     Galena,  fluorite,  and  magnetite 
illustrate  such  combinations. 

Trapezohedron.—  The  trapezohedron  (Fig.  105)  has  twenty-four 
similar  faces,  each  of  which  is  a  trapezium.  Each  face  intersects 
one  axis  at  a  certain  distance  (unity)  and  the 
other  two  at  equal  multiples  of  unity.  This 
form  has  two  kinds  of  edges  and  three  kinds  of 
solid  angles.  A  trapezohedron  having  the 
symbol  (211)  is  the  common  form  of  garnet, 
analcite,  and  leucite.  One  with  the  symbol 
(311)  would  differ  from  the  one  figured  in  its  FIG.  105. 

interfacial  angles,  although  the  arrangement  of  the  faces  would 
be  similar. 


172 


ISOMETRIC    SYSTEM. 


Fig.  106  (garnet)  represents  the  trapezohedron  n  (211)  in  com- 
bination with  the  dodecahedron  d  ;  Fig.  107  (analcite),  a  combina- 


FIG.  >06.  FIG.  107.  FIG.  108. 

tion  of  the  same  trapezohedron  n  with  the  cube  a ;  and  Fig.  108 
(magnetite),  the  trapezohedron  m  (311)  with  the  dodecahedron  d. 

Trisoctahedron.— This  form  has  twenty -four  triangular  faces, 
each  cutting  two  of  the  axes  at  unity  and  the  third  at  a  multiple 
of  unity.  The  one  shown  in  Fig.  109  has  the  symbol  (221).  Fig. 
110  represents  a  combination  of  this  form  p  (221)  with  the  octa- 
hedron o,  which  occurs  in  galena 

Tetrahexahedron. — This    form    has    twenty-four    triangular 


FIG.  109.  FIG.  110.  FIG.  111.  FIG.  112. 

faces,  each  cutting  one  axis  at  unity,  a  second  at  a  multiple  of 
unity,  and  a  third  at  infinity.  The  one  shown  in  Fig.  Ill  has 
the  symbol  (210).  Fig.  112  is  a  combination  of  /  (310)  with  the 
cube  a,  which  occurs  in  fluorite. 

Hexoctahedron.— This  form  has  forty-eight  triangular  faces. 


FIG.  113. 


FIG.  114. 


FIG.  115. 


PYRITOHEDRAL  GROUP. 


173 


each  cutting  one  axis  at  unity  and  the  other  two  at  different 
multiples  of  unity.  The  one  shown  in  Fig.  113  has  the  symbol  (321 ). 
Fig.  114  (garnet)  represents  a  combination  of  this  form  s  (321)  with 
the  dodecahedron  d,  and  Fig.  115  (fluorite),  the  hexoctahedron  t  (421) 
with  the  cube  a.  Such  combinations  are  only  occasionally  observed. 
There  are  in  all  seven  kinds  of  simple  forms  in  the  normal 
group :  the  cube,  octahedron,  dodecahedron,  trapezohedron,  tris- 
octahedron,  tetrahexahedron,  and  hexoctahedron.  It  is  possible 
that  an  isometric  mineral  may  crystallize  in  any  of  these  forms, 
although  usually  there  are  certain  forms  and  combinations  which 
are  especially  common  in  and  characteristic  of  individual  species. 
Thus  galena  and  fluorite  crystallize  usually  in  cubes  and  octa- 
hedrons, or  their  combinations ;  magnetite,  in  octahedrons  and 
dodecahedrons,  or  their  combinations ;  garnet,  in  dodecahedrons 
and  trapezohedrons  (211),  or  their  combinations  ;  and  leucite  and 
analcite,  in  trapezohedrons  (211).  It  is  very  seldom  that  galena  is 
found  in  dodecahedrons,  magnetite  in  cubes,  or  garnet  in  either 
cubes  or  octahedrons. 

ISOMETRIC   FORMS    OF   LOWER    SYMMETRY    THAN    THAT   PRESENTED 
BY    THE   NORMAL   GROUP. 

Pyritolieclral  Group. — Pyrite  Type. 

Crystals  of  this  group  are  characterized  by  having  three  axes 
of    binary   and    four    of    trigonal    symmetry 
(Fig.  116)  ;    also   three  axial  planes   of  sym- 
metry (Fig.  93.  p.  170). 

Pyritohedron. — This  form  (Fig.  117),  some- 
times called  the  pentagonal  dodecahedron,  has 
twelve  pentagonal  faces,  corresponding  in 
position  to  the  alternating  faces  of  the  tetra- 
hexahedron. The  symbol  of  the  pyritohedron  figured  is  (210),  the 
same  as  that  of  the  tetrahexahedron  (Fig.  111). 

Diploid. — This  form  (Fig.  118)  has  twenty-f our  faces  which  cor- 
respond in  position  to  half  of  the  faces  of  the  hexoctahedron.  The 
symbol  of  the  diploid  figured  is  (321),  the  same  as  that  of  the 
hexoctahedron  (Fig.  113). 


FIG.  116. 


174 


ISOMETRIC   SYSTEM. 


The  cube,  octahedron,  dodecahedron,  trisoctahedron,  and  trap* 
ezohedron  occur  in  this  group,  but  they  differ  from  the  forms  of 
the  normal  group  in  having  a  lower  kind  of  symmetry.  Thus  it 
may  generally  be  observed  that  the  cubes  of  pyrite  are  striated, 


FIG.  117. 


FIG.  118. 


FIG.  119. 


the  striae  running  in  one  direction  on  each  cubic  face,  and  at  right 
angles  to  one  another  on  adjacent  faces  (Fig.  119).  The  striations 
result  from  the  tendency  of  the  cube  to  crystallize  in  combination 
with  the  pyritohedron  (Fig.  117).  The  crystallographic  axes  of 
such  striated  cubes  are  axes  of  binary  symmetry,  and  not  of  tet- 
ragonal symmetry  ;  therefore  the  cubes  are  not  normal  ones.  Turn 
a  cube  of  galena  about  its  vertical  axis  and  it  will  present  the 
same  appearance  four  times  during  a  complete  revolution,  but  a 
striated  cube  of  pyrite  similarly  turned  will  present  the  same 
appearance  only  twice. 


FIG.  120. 


FIG.  121. 


FIG.  122. 


FIG.  123. 


FIG.  124.  FIG.  125.  FIG.  126. 

The  combinations  of  the  cube  a  (100)  and  the  octahedron  o  (111) 
with  the  pyritohedron  e  (210)  and  the  diploid  t  (421),  represented 


TETRAHEDRAL     GROUP. 


175 


by  Figs.  120  to  125,  illustrate  forms  which  may  be  observed  in 
pyrite  and  cobaltite,  all  of  which  serve  to  show  the  characteristic 
symmetry  of  this  group.  Fig.  126  represents  a  penetration  twin 
of  two  pyritohedrons. 

Tetrahedral  Group. — TetraJiedrite  Type. 

Crystals  of  this  type  are  characterized  by 
having  three  axes  of  binary  and  four  of  trigo- 
nal symmetry  (Fig.  127),  and  also  six  diagonal 
planes  of  symmetry  (Fig.  94,  p.  170).  The  com- 
monest form  is  the  tetrahedron,  from  which 
the  group  derives  its  name.  FlQ  127 

Tetrahedron.— This  form  o  ( 111)  (Fig.  128)  has  four  faces, 
corresponding  in  position  to  the  alternating  faces  of  the  octahe- 
dron (Fig.  96).  The  faces  are  equilateral  triangles,  and  the  inter- 
facial  angles  are  alike,  109°  28'.  Two  tetrahedrons  are  possible 
which  differ  in  position  ;  o  (111)  (Fig.  128)  being  designated  as  the 
positive  tetrahedron  and  ol  (111)  (Fig.  129),  as  the  negative.  The 
crystallographic  axes  join  the  centers  of  opposite  edges.  The 
positive  and  negative  tetrahedrons  may  occur  in  combination,  as 
represented  by  Fig.  133. 


FIG.  138. 


FIG.  129. 


Tristetrahedron.  —  This    form    has    twelve    triangular  faces, 
corresponding  in  position  to  half  of  the  faces 
of  the  trapezohedron   (Fig.    105).     The   form 
represented  by  Fig.  130  has  the  symbol  (211). 

Possible  forms  in  this  group,  which  are 
occasionally  seen  in  combination  with  other 
forms,  are  the  deltoid  dodecahedron  (Fig.  131) 
and  the  Tiexakistetrahedron  (Fig.  132),  whose  faces  correspond 


-  18°- 


ISOMETRIC    SYSTEM. 


to  half  of  those  of  the  trisoctahedron  (Fig.  109)  and  the  hexocta- 
hedron  (Fig.  113),  respectively. 


FIG.  131. 


FIG.  132. 


The  cube  a  (100),  the  dodecahedron  d  (110),  and  the  tetrahexa 
hedron  occur  in  combination  with  the  foregoing  tetrahedral  forms, 
From  Fig.  127  it  may  be  seen  that  in  the  cube  of  this  group  the 
diagonally  opposite  solid  angles  are  not  alike.  This  is  further 
shown  by  the  combination  of  the  cube  and  tetrahedron  (Fig.  134). 
By  comparing  Figs.  134  and  137  with  Figs.  98  and  103,  respectively, 
it  will  be  seen  that  both  the  cube  and  dodecahedron  of  this  group 
differ  from  the  normal  cube  and  normal  dodecahedron  of  the 
galena  type. 

Tetrahedrite,  sphalerite,  and  bora  cite. occur  in  tetrahedrons  and 
tetrahedral  combinations,  and  Figs.  133  to  138  represent  some  of 
the  combinations  which  may  be  observed,  where  o  is  the  positive 


FIG.  133. 


FIG.  134. 


FIG.  135. 


FIG.  136.  FIG.  137.  FIG.  13«. 

and  o,  the  negative  tetrahedron,  a  the  cube,  d  the  dodecahedron, 
and  n  the  tristetrahedron  (211). 


TETRAGONAL   SYSTEM. 


177 


TETRAGONAL  SYSTEM. 

The  forms  in  this  system  are  referred  to  three  axes,  all  at  right 
angles  to  one  another.  The  two  lateral  axes  a  (Fig.  139)  are  equal 
and  interchange,  while  the  vertical  axis  c 
differs  from  these  in  length  andin  charac- 
ter. The  length  of  the  vertical  axis  has  to 
be  determined  by  the  measurement  of  ap- 
propriate angles  for  each  substance  crystal- 
lizing in  this  system.  In  zircon,  for  ex- 
ample, c  —  0.640,  a  being  taken  as  unity. 

Forms  of  the  Normal  Group. — Zircon  Type. 
The  crystals  of  this  group  are  characterized  by  having  a  vertical 
axis  of  tetragonal  symmetry  and  four  axes  of  binary  symmetry 
(Fig.  140)  ;   also  one  horizontal  and  four  vertical  planes  of  sym- 
metry (Fig.  141). 


^ 

•^ 

». 

^-j-H 

ft-! 

K, 

Ut- 

..IB-—  j—  jp" 
i  
.-''"'           •« 

"'1 

r=» 

1 

/ 

FIG.  140.  FIG.  141. 

The  forms  are  of  three  kinds :  pyramidal,  when  the  faces 
intercept  the  vertical  and  one  or  both  of  the  horizontal  axes  ;  pris- 
matic, when  the  faces  are  parallel  to  the  vertical  axis  ;  and  pina- 
coidal,  when  the  faces  are  parallel  to  the  horizontal  axes. 

Pyramids. — A  form  known  as  the  pyramid  of  the  first  order 
(Fig.  142)  has  the  symbol  (111),  where  the  third  index  refers  to  the 
characteristic  length  of  the  vertical  axis.  This  form  is  character- 
ized by  having  eight  similar  faces  which  are  isosceles  triangles, 
two  kinds  of  edges,  and  two  kinds  of  solid  angles.  (Compare  the 
isometric  octahedron  (111),  Fig.  96).  Pyramids  of  this  order  are 
alike  in  the  general  arrangement  of  their  faces,  but  those  of  differ- 
ent minerals  will  not  have  the  same  interfacial  angles,  since 


178 


TETRAGONAL   SYSTEM. 


the  lengths  of  their  vertical  axes  are  not  alike.  Fig.  145  represents 
the  pyramid  in  zircon  where  c  =  0.640  ;  Fig.  143,  one  of  braunite 
where  c  =  0.985  (the  interfacial  angles  in  this  case  are  near  those  of 
the  isometric  octahedron,  Fig.  96) ;  and  Fig.  144,  one  of  octahedrite 
where  c  =  1.777. 


FIG.  142. 


FIG.  143. 


FIG.  144. 


Another  form,  known  as  the  pyramid  of  the  second  order  (Fig. 
145),  has  the  symbol  (101).  This  form,  like  that  of  the  pyramid  of 
the  first  order,  has  eight  similar  faces  which  are  isosceles  triangles, 
two  kinds  of  edges,  and  two  kinds  of  solid  angles.  Fig.  145  repre- 
sents the  pyramid  of  the  second  order  of  zircon  where  c  =  0.640. 

On  any  mineral  there  may  be  steeper  or  flatter  pyramids  than 
the  unit-forms  (111)  and  (101),  according  as  the  faces  intercept  the 
vertical  axis  at  a  multiple  or  fraction  of  its  characteristic  length. 


FIG.  145. 


FIG.  146. 


Fig.  146  represents  a  form  known  as  the  ditetragonal  pyramid, 
having  eight  similar  faces  above  and  eight  below.  Its  symbol  is 
(311),  and  the  vertical  axis  corresponds  to  that  of  zircon,  c  =  0.640. 


NORMAL    GROUP. 


179 


Prisms.— Square  prisms  are  very  common  and  characteristic 
forms  in  this  group.  The  form  m  (110)  (Fig.  147)  is  called  a  prism 
of  the  first  order  and  the  form  a  (100)  (Fig.  148)  a  prism  of  the  sec- 
ond order.  Each  consists  of  four  similar  faces  with  interfacial 
angles  of  exactly  90°. 

Fig.  149  represents  a  form  (210)  which  has  eight  similar  faces 
and  is  known  as  a  ditetragonal  prism. 

Fig.  150  is  a  plan,  or  horizontal  projection  of  the  lateral  axes, 
together  with  the  trace  of  the  prism  of  the  first  order  m  and 
the  second  order  a.  The  necessity  for  having  prisms  and  pyra- 
mids of  two  orders  will  become  evident  when  the  tetragonal 
combinations  are  considered. 


210 


2  O. 


a  100 


FIG.  147. 


FIG.  148. 


There  is  nothing  in  the  molecular  character  of  a  substance 
to  determine  the  length  of  its  prismatic  forms,  as  the  prisms 
which  occur  on  a  mineral  may  be  either  long  or  short,  wholly  inde- 
pendent of  the  characteristic  length  of  the  vertical  axis  c.  The 
pyramidal  faces  which  terminate  the  prisms  have,  however,  definite 
inclinations,  and  from  the  angles  of  these  the  length  of  the  vertical 
axis  c  is  calculated. 

Base  or  Pinacoid.  —  The  form  c  (001)  is  a  very  common  one,  and 
consists  of  two  similar  parallel  faces,  the  top  and  bottom  ones  in 
Figs.  147  to  149. 

Combinations.  —  The  following  examples  will  serve  to  show  the 
variations  in  habit  resulting  from  the  combinations  of  tetragonal 
forms  in  different  minerals.  The  frequent  occurrence  of  the  forms 
with  simple  indices  is  noticeable  :  a  (100),  c  (001),  m  (110), 
p  (111),  and  e  (101). 


180 


TETRAGONAL   SYSTEM. 


The  interfacial  angles  a  A  a,  m  A  w,  a  A  <?,  and  ra  A  c  =  90° 
and  a  A  m  =  45°. 

Zircon  (Figs.  142  and  151  to  155).— Axis  <?=  0.640.  Angles 
p  Ap  =  56°  40'  and  c  A  ^  =  42°  10'.  These  crystals  commonly  pre- 
sent the  combination  of  the  prism  of  the  first  order  m  (110)  with 


FIG.  151.  FIG.  152.  FIG.  153.  FIG.  154.  FIG.  155. 

the  pyramid  of  the  first  order  p  (111).  The  steep  pyramid  of  the 
first  order  u  (331)  and  the  ditetragonal  pyramid  x  (311)  are  occa- 
sionally observed.  The  base  c  (001)  is  exceeding  rare  on  zircon 
crystals. 

Vesumanite  (Figs.  156  to  159).— Axis  c  =  0.537.  Angles  pf\p  = 
50°  39'  and  c  A  p  =  37°  13'.  These  crystals  usually  show  the  prism 
of  the  first  order  m  (110)  and  of  the  second  order  a  (100),  ter- 


FIG.  156.  FIG.  157.  FIG.  158.  FIG.  159. 

minated  either  by  the  basal  plane  c  (001),  the  pyramid  of  the  first 
order^  (111),  or  by  a  combination  of  both  c  and#>. 

Cassiterite  (Figs.  160  to  162).— Axis  c  =  0.672.  Angles^  Ap  = 
58°  19'  and  c  /\p  =  43°  33'.  On  crystals  of  this  mineral  the  pyra- 
mid and  prism  of  the  first  order,  p  (111)  and  m  (110),  and  the  prism 
of  the  second  order  a  (100)  are  the  prominent  forms.  The  pyra- 
mid of  the  second  order  e  (101)  and  the  base  c  (001)  occur  in  com- 


NORMAL    GROUP.  181 

bination  with  these.     Twin  crystals  are  common  with  the  pyramid 


FIG.  160.  FIG.  161.  FIG.  162. 

of  the  second  order  e  (Oil)  as  twinning-plane. 

Entile  (Figs.  163  to  166).— Axis  c  =  0.644.  Angles  p  Ap  = 
56°  52'  and  c  A  p  =  42°  20'.  The  crystals  are  usually  prismatic  and 
often  capillary.  Prisms  of  the  first  and  second  orders,  m  (110)  and 


FIG.  163.  FIG.  164.  FIG.  165.  FIG.  166. 

a  (100),  occur  and  are  terminated  by  the  pyramids  of  the  first  and 
second  orders,  p  (111)  and  e  (101).  Fig.  164  is  a  basal  projection 
of  Fig.  163,  and  shows  the  symmetrical  development  of  the  faces 
of  a  tetragonal  crystal  about  the  vertical  axis.  Twin  crystals  of 
rutile  are  very  common,  a  pyramid  of  the  second  order  (101)  being 
the  twinning-plane.  Often  a  network  of  prisms,  crossing  at  angles 
of  nearly  60°  and  120°  (Fig.  165),  and  zigzag  groups  (Fig.  166) 
result. 

Octahedrite  (Figs.  1 67  and(168).— Axis  c  =  1 . 777.  Angles  p  A  p  = 
82°  9'  and  c  A  p  =  68°  18'.  The  common  form  is  the  pyramid  of 
the  first  order  p  (111)  (Fig.  144). 
The  forms  shown  in  Figs.  167  and 
168  are  the  fiat  pyramids  of  the 
first  and  second  orders,  z  (113) 
and  x  (103),  the  prism  of  the  first 
order  a  (100),  and  the  base  c  (001). 

Apophyllite  (Figs.  169  to  172).— Axis  c  =  1.251.    Angles^  /\p  = 
76°  0'  and  c  A  p  =  60°  32'.  This  mineral  is  characterized  by  the  almost 


FIG.  107. 


FIG.  168. 


182  TETRAGONAL   SYSTEM. 

constant  occurrence  of  the  pyramid  of  the  first  order  p  (111)  in 


FIG.  169  FIG.  170.  FIG.  171.  FIG.  172. 

combination  with  the  prism  of  the  second  order  a  (100).  The  basal 
plane  c  (001)  is  usually  present,  and  is  often  prominent  (Fig.  172). 
The  ditetragonal  prism  y  (310)  may  also  occasionally  be  observed. 

TETRAGONAL  FORMS  OF  LOWER  SYMMETRY  THAN  THAT  PRESENTED 
BY  THE  NORMAL  GROUP. 

Tri-Pyr  amidol  Group. — Scheelite  Type. 

This  group  is  characterized  by  having  a  vertical  axis  of  tetrag- 
onal symmetry  and  one  horizontal  plane  of  symmetry.  (Compare 
Figs.  140  and  141,  p.  177). 

The  characteristics  of  the  group  may  be  illustrated  by  scheelite 
and  scapolite. 

ScTieelite  (Figs.  173  and  175).— Axis  c  =  1.536.  Angles^?  A  p  = 
79°  55'  and  c  /\p  =  65°  16'.  Fig.  173  represents  a  combination  of 


FIG.  173.  FIG.  174.  FIG.  175. 

the  pyramid  of  the  first  order  p  (111),  of  the  second  order  e  (101), 
and  a  form  s  having  the  symbol  (131)  and  known  as  a  pyramid 
of  the  third  order.  If  the  form  s  occurred  alone  it  would  be  a 
tetragonal  pyramid,  with  its  horizontal  edges  having  the  directions 
3  a :  a  on  the  lateral  axes.  A  pyramid  of  the  third  order  (133),  not 


SPHEROIDAL   GROUP. 


183 


so  acute  as  the  form  s,  is  represented  by  Fig.  174.  A  common 
habit  with  scheelite  is  a  combination  of  the  pyramids  of  the  first 
and  second  orders,  p  and  e  (Fig.  175). 

Scapolite  (Figs.  176  to  178).— Axis  c  =  0.438.     Angles  p  A  p  = 
43°  45'  and  c  /\p  =  31°  48'.   The  figures  illustrate  combinations  of 


FIG.  176.  FIG.  177.  FIG.  178. 

the  prisms  of  the  first  and  second  orders,  m  (110)  and  a  (100),  with 
the  pyramid  of  the  first  order  p  (111);  while  Fig.  178  shows  the 
additional  pyramid  z  (311)  of  the  third  order. 

It  should  be  observed  that  the  forms  s  (131)  of  scheelite  and 
z  (311)  of  scapolite  are  tetragonal  pyramids,  while  the  form  with 
corresponding  indices  in  the  normal  group  is  a  ditetragonal  pyra- 
mid (Fig.  146). 

Sphenoidal  Group. — Chalcopyrite  Type. 

This  group  is  characterized  by  having  a  vertical  axis  of  binary 
symmetry  and  two  horizontal  axes  of  binary  symmetry ;  also 
two  vertical  planes  of  symmetry  (numbers  4  and  5)  (Fig.  141,  p.  177). 
The  forms  are  illustrated  by  chalcopyrite. 

Chalcopyrite  (Figs.  179  to  185). — Axis  c  =  0.985.  Angles^?  A  .£>,= 
70°  7%'  and  c  /\p  =  54°  20'.  The  form^?  (Ill)  (Fig.  179)  is  called  a 


FIG.  179.  FIG.  180.  FIG.  181.  FIG.  182. 

sphenoid.    It  has  four  similar  faces,  which  correspond  in  their  re- 
lation to  the  axes  to  the  alternating  faces  of  the  tetragonal  pyra- 


184  HEXAGONAL   SYSTEM. 

mid  of  the  first  order  (Fig.  143).  The  form  is  analogous  to  the 
isometric  tetrahedron  (Fig.  128),  being  almost  identical  with  it  in 
its  interfacial  angles,  since  the  length  of  the  vertical  axis  of  chal- 
copyrite  is  so  nearly  equal  to  that  of  the  lateral  axes.  The  posi- 
tive sphenoid  p  (111)  and  the  negative  sphenoid  p  (111)  occur  in 
combination  (Fig.  180),  also  twinned  (Fig.  181).  The  acute  sphe- 
noid r  (Fig.  182)  having  the  symbol  (332)  and  the  pyramid  of  the 
second  order  z  (Figs.  183  and  184)  having  the  symbol  (201)  are 
occasionally  observed.  The  twinning-plane  of  Figs.  181  and  184  is 
(111).  Fig.  185  represents  a  combination  of  an  acute  sphenoid 


FIG.  183.  FIG.  184.  FIG.  185. 

#  (772)  with  a  form  x  (122),  known  as  a  scalenohedron,  but  the 
symbols  of  these  two  forms  are  questionable,  because  the  faces 
are    striated  and  the  inclinations  therefore  not  accurately  de 
termined. 

HEXAGONAL  SYSTEM. 

The  forms  in  this  system  are  referred  to  four  axes.  TTic 
three  lateral  axes  an  aa,  and  a3  (Fig.  186)  are  equal  and  inter- 
changeable, and  cross  at  angles  of  60°  and  120°,  while  the  vertical 
axis  c  is  of  different  length  and  at  right  angles  to  them.  The 
length  of  the  vertical  axis  must  be  determined  by  the  measurement 
of  appropriate  angles  for  each  substance  crystallizing  in  this  sys- 
tem. In  beryl,  for  example,  c  =  0.499,  the  lateral  axes  being 
taken  as  unity. 

Fig.  187  represents  a  plan  of  the  lateral  axes.  In  giving  the 
parameters  and  indices  of  the  forms,  the  order  in  which  the  axes 
are  taken,  a,,  a3,  and  &s,  and  also  the  positive  and  negative  direc- 
tions, as  indicated  in  the  figure,  should  be  carefully  observed. 


NORMAL    GROUP. 


185 


On  account  of  the  axial  angles  of  60°  and  120°  there  are  certain 
relations  of  the  crystal  faces  to  the  horizontal  axes,  represented  by 
Fig.  188,  which  should  be  carefully  considered.  A  face  intersect- 
ing the  unit  lengths  of  adjacent  axes  will  be  parallel  to  the  third 
axis  ;  hence  the  parameter  relation  a1 :  oo  a, :  —  a3  and  indices  (101). 
A  face  going  from  unity  (a)  on  one  axis  to  a  multiple  of  unity 

rn 

(no)  on  an  adjacent  axis  will  intersect  the  third  axis  at  — — ^a, 

Thus  when  n  =  2,  the  face  may  have  the  parameter  relation 
2a, :  2a, :  —  a3  and  indices  (112).  When  n  is  a  quantity  greater  than 
1  and  less  than  2,  for  example  f ,  the  parameter  relation  may  be 
fa^  :  3aa :  —  a3,  indices  (213).  In  every  case  the  third  index  will  be 


a »       -a2 


-a3 


-c 
FIG.  186. 


4Ct2 


FIG.  187. 


FIG.  188. 


equal  to  the  sum  of  the  first  and  second  indices,  with  the  opposite 
sign.  In  the  complete  symbols  of  hexagonal  forms  there  will  be 
a  fourth  index,  expressing  the  relation  on  the  vertical  axis. 

Forms  of  the  Normal  Group. — Beryl  Type. 

The  crystals  of  this  group  are  characterized  by  having  a  vertical 
axis  of  hexagonal  symmetry  and  six  horizontal  axes  of  binary  sym- 
metry (Fig.  189)  ;  also  one  horizontal  and  six  vertical  planes  of 
symmetry  (Fig.  190). 

The  forms  are  of  three  kinds  :  pyramidal,  when  the  faces  in- 
tersect the  vertical  and  the  horizontal  axes  ;  prismatic,  when  the 
faces  are  parallel  to  the  vertical  axis ;  and  pinacoidal,  when  the 
faces  are  parallel  to  the  three  horizontal  axes. 


186 


HEXAGONAL   SYSTEM. 


FIG.  189. 


FIG.  190. 


Pyramids.— A  form  known  as  the  pyramid  of  the  first  order 
(Fig.  191)  has  the  symbol  (1011).  The  twelve  faces,  six  above  and 
six  below,  are  alike,  and  are  isosceles  triangles.  The  six  upper 
ones  have,  respectively,  the  following  indices  :  (1011),  (Olll),  (1101), 
(1011),  (0111),  (1101).  A  form  known  as  the  pyramid  of  the  second 
order  (Fig.  192)  has  the  symbol  (ll£2) ;  in  this  the  twelve  faces 
are  isosceles  triangles,  the  six  upper  ones  having  the  following 
indices:  (1122),  (1212),  (2112),  (1122),  (1312),  (2112).  There  may 
be  steeper  or  flatter  pyramids  of  either  order,  according  as  the 


32fi- 


FIG.  191.  FIG.  192.  FIG.  193. 

vertical  axes  are   cut  at  a  multiple  or  a  fraction  of  the  unit 
length. 

Fig.  193  represents  a  form  with  twelve  similar  faces  above  and 
twelve  below,  known  as  the  dihexagonal  pyramid.  It  is  only 
occasionally  that  a  complicated  form  of  this  kind  is  observed  in 
combinations.  One  is  shown  in  Fig.  203  (beryl)  lettered  n.  The 
form  represented  by  Fig.  193  has  the  symbol  (2131),  where 
c  =  0.499,  the  length  of  the  vertical  axis  of  beryl. 


NORMAL   GROUP. 


187 


Prisms. — Corresponding  to  the  pyramids  are  two  hexagonal 
prisms :  the  prism  of  the  first  order,  m  (Fig.  194),  with  the 
symbol  (1010),  and  the  prism  of  the  second  or,der,  a  (Fig.  195),  with 
the  symbol  (1120).  Each  kind  of  prism  has  six  similar  faces,  with 
interfacial  angles  of  60°. 


^  .  —  • 

0001   c 

J\ 

i 

! 

1100 

ioib 
j 

ojio 

m 

mi 

m 

i 

^ 

1 

^> 

fd 

(X 

01 

c         ^ 

2110 

1120 

a 

* 

^" 

a         a 

£~^ 

? 

FIG.  194.  FIG.  195. 

Fig.  196  gives  a  plan  of  the  horizontal  axes,  together  with 
the  trace  of  the  prism  of  the  first  order  m  and  of  the  second  order 
a.  The  necessity  of  having  pyramids  and  prisms  of  the  two  orders 
will  become  evident  when  some  of  the  crystal  combinations  are 
considered. 


oopi 

i 

i  j 

i 

i! 

i 

-*-._ 

KJ 

^ 

=t 

3120 

pi^o 

! 

i  i 

i 

j 

-L 

FIG.  196.  FIG.  197. 

rare  diJiexagonal  prism  having  twelve  similar  faces  is 
shown  by  Fig.  197,  which  represents  the  form  (2130). 

The  prisms  of  a  hexagonal  mineral  may  be  either  long  or  short, 
wholly  independent  of  the  characteristic  length  of  the  vertical 
axis. 

Base  or  Pinacoid.— The  form  c,  having  the  symbol  (0001),  con- 
sists of  two  similar  faces,  the  top  and  bottom  ones  of  Figs.  194,  195, 
and  197.  The  basal  plane  is  exactly  at  right  angles  to  the  pris- 
matic faces. 


188 


HEXAGONAL   SYSTEM. 


Combinations. — The  following  representations  of  crystals  of 
different  minerals  illustrate  some  combinations  of  hexagonal  forms. 
In  these  the  prevalence  of  the  forms  with  simple  indices,  c  (0001), 
m  (1010),  andp  (1  Oil)  is  noticeable.  The  interfacial  angles  m  A  c  and 
a  A  c  —  90°,  m  i\m  and  a  A  a  =  60°,  and  m  A  a  =  30°. 

Beryl  (Figs.  198-203).— Axis  c  =  0.499.  Angles  p  A  p  =  28°  54' 
and  c  A  p  =  29°  56'.  The  common  habit  of  beryl  is  a  combination 
of  the  prism  of  the  first  order,  m  (1010),  with  the  base  c  (0001). 
Crystals  showing  pyramidal  forms  of  the  first  order,  p  (1011), 
and  of  the  second  order,  s  (1121),  and  the  prism  of  the  second 
order,  a  (1120),  are  rather  exceptional.  Fig,  202  is  a  basal 


FIG.  198. 


FIG.  199. 


FIG.  200. 


FIG.  201. 


FIG.  202. 


FIG.  203. 


projection  of  Fig.  201,  illustrating  the  development  of  similar 
faces  in  sets  of  six  about  the  vertical  axis.  Fig.  203  represents  a 
highly  modified  crystal,  with  the  prism  m,  terminated  by  a  dihex- 
agonal  pyramid  n  (3141),  two  pyramids  of  the  second  order,  s  and 
d  (3364),  the  pyramid  of  the  first  order  p,  and  the  base  c. 

Pyrrliotite  (Figs.  204  and  205). —Axis  c  —  0.870.  Angles 
p  A  p  =  41°  30'  and  c  A  p  =  45°  8'.  The  crystals  of  this  mineral  are 
usually  tabular,  owing  to  the  prominence  of  the  base  c  (0001),  and 


PYRAMIDAL    GROUP. 


189 


show  the  forms  of  the  prism  of  the  first  order  m  (101 0),  and  two 
pyramids  of  the  first  order,  p  (1011)  and  u  (4041). 


FIG.  204. 

Hanksite  (Fig.  206).— Axis  c  =  1.014.  Angles  p  /\p  =  44°  41' 
and  c  A  p  =  49°  30'.  The  common  combination  is 
that  of  the  prism  and  pyramid  of  the  first  order, 
m  (1010)  and  p  (1011),  with  the  basal  plane 

c  (0001). 
FIG.  206. 


HEXAGONAL    FORMS    OF  LOWER   SYMMETRY  THAN  THAT   PRESENTED 
BY  THE  NORMAL  TYPE. 

Tri-Pyramidal  Group. — Apatite  Type. 

This  group  is  characterized  by  having  a  vertical  axis  of  hex- 
agonal symmetry  and  one  horizontal  plane  of  symmetry.  (Com- 
pare Figs.  189  and  190.) 

The  characteristics  of  the  group  may  be  illustrated  by  apatite 
and  vanadinite. 

Apatite  (Figs.  207,  209  and  210).— Axis  c  =  0.735.  Angles  p  A  p 
=  37°  44'  and  c  A  p  =  40°  18'.  Fig.  207  represents  a  somewhat  com- 
plex crystal,  with  the  prisms  of  the  first  and  second  orders,  m  (1010) 
and  a  (1120),  terminated  by  the  base  c  (0001),  three  pyramids  of 
the  first  order,  y  (2021),  p  (1011),  and  r  (1012),  a  pyramid  of  the 


FIG.  207.  FIG.  208. 

second  order  s  (1121),  and  a  hexagonal  pyramid  //  (2131),  known 
as  a  pyramid  of  the  tliird  order. 


190 


HEXAGONAL    SYSTEM. 


A  pyramid  of  the  third  order  having  the  symbol  (1233),  but  not 
so  acute  as  the  form  /*,  is  represented  by  Fig.  208.  It  will  be 
observed  that  the  horizontal  axes  do  not  join  the  opposite  solid 
angles,  as  in  the  pyramid  of  the  first  order  (Fig.  191),  nor  the 
centers  of  opposite  edges,  as  in  the  pyramid  of  the  second  order 
(Fig.  192).  The  simple  crystals  of  apatite  which  are  ordinarily 
observed  (Figs.  209  and  210)  do  not  appear  to  differ  from  forms  of 
the  normal  group,  but  their  peculiar  symmetry  can  be  revealed  by 
etching  with  acid,  as  explained  beyond  under  quartz  (page  198). 


FIG.  209. 


FIG.  210. 


FIG.  211. 


Vanadinite  (Fig.  211).— Axis  c  =  0.712.  The  figure  illustrates 
a  rather  simple  combination  of  a  prism  of  the  first  order  m  (1010) 
and  base  c  (0001),  with  a  pyramid  of  the  third  order  ^  (2131). 

It  should  be  observed  that  the  form  /*  (2131)  in  this  group  is 
a  hexagonal  pyramid,  while  in  the  normal  group  a  form  with 
corresponding  indices  is  a  dihexagonal  pyramid  (Fig.  193). 


HemimorpMc  Group. — lodyrite  Type. 

This  group  is  characterized  by  having  a  vertical  axis  of  hex- 
agonal symmetry  and  six  vertical  planes  of  symmetry.  The 
peculiarity  of  the  crystals  is  the  development  of  different  forms  at 
opposite  extremities  of  the  vertical  axis,  as  illustrated  by  Fig.  212 
of  the  rare  mineral  iodyrite,  and  Fig.  213  of  zincite.  The  pyramids 
of  iodyrite  are  u  (4041)  and  n  (4043). 


RHOMBOHEDRAL  GROUP. 


191 


FIG.  212. 


FIG.  213. 


RHOMBOHEDKAL  FORMS  OF  THE  HEXAGONAL  SYSTEM. 

In  crystals  of  this  class  the  forms  are  referred  to  the  hexagonal 
system  of  axes  (Fig.  186),  but  the  vertical  axis  c  is  one  of  trigonal 
and  not  of  hexagonal  symmetry.  Many  common  minerals  crystal- 
lize in  this  class,  which  is  often  designated  as  the  rhomboTiedral 
system. 

Forms  of  the  Normal  Khomboliedral  Group. — Calcite  Type. 

The  forms  of  this  group  are  characterized  by  having  a  vertical 
axis  of  trigonal  symmetry  and  three  horizontal  axes  of  binary  sym- 


FIG.  214.  FIG.  215.  FIG.  216. 

metry  (Fig.  214)  ;    also  by  having  three  vertical  planes  of  sym- 
metry, 4,  5,  and  6  (Fig.  190,  p.  186). 

Rhombohedrons.— A  rhombohedron  (Fig.  215)  is  characterized 
by  having  six  similar  faces  which  are  rhombs  and  correspond  in 
their  axial  relations  to  the  alternating  faces  of  the  hexagonal  pyra- 
mid of  the  first  order  (Fig.  191).  Rhombohedrons  are  designated 
as  positive  (Fig.  215)  when  a  face  above  is  toward  the  observer,  and 
negative  (Fig.  216)  when  an  edge  above  is  toward  the  observer. 


192  HEXAGONAL    SYSTEM. 

When  the  faces  intercept  the  vertical  axis  at  unity,  the  symbols 
of  these  forms  are,  respectively,  (1011)  and  (0111).  Furthermore, 
rhombohedrons  are  called  obtuse  or  flat  when  the  solid  angles  at 
the  extremities  of  the  vertical  axis  are  obtuse,  and  acute  or  steep 
when  these  solid  angles  are  acute.  Fig.  218  represents  an  obtuse, 
and  Fig.  221,  an  acute  rhombohedron  of  calcite.  They  also  have 
two  kinds  of  solid  angles  ;  those  at  the  extremities  of  the  vertical 
axis,  where  the  plane  angles  of  the  faces  are  alike,  and  six  others 
in  which  the  plane  angles  of  the  faces  are  of  two  kinds,  either  two 
acute  and  one  obtuse  (Fig.  218),  or  two  obtuse  and  one  acute  (Fig. 
221).  The  edges  are  of  two  kinds,  six  (three  above  and  three  be- 
low) running  to  the  extremities  of  the  vertical  axis,  and  six  going 
zigzag  around  the  crystal. 

Scalenohedron. — This  is  a  form  (Fig.  217)  having  twelve  similar 
faces,   six  above  and  six  below,  corresponding  in 
position  to  the    alternating  pairs  of  faces  of  the 
dihexagonal  pyramid    (Fig.    193).     The  faces    are 
scalene  triangles,  hence  the  name  scalenohedron. 
The  edges  which  meet  at  the  extremities  of  the  ver- 
tical axis  are  of  two  kinds,  long  and  short,  alter- 
nately disposed;   while  the  six  middle  edges  are 
alike,  and  run  zigzag  around  the  crystal,  as  in  the 
FlGY217          rhombohedron  (Fig.  215).     Fig.  217  represents  the 
scalenohedron  (2131)  which  commonly  occurs  on  calcite. 

Combinations. — Pyramids  of  the  second  orders  (Fig.  192), 
prisms  m  and  a  of  the  first  and  second  orders  (Figs.  194  and  195), 
the  dihexagonal  prism  (Fig.  197),  and  the  basal  plane  c  (0001)  oc- 
cur in  combination  with  rhombohedrons  and  scalenohedrons.  The 
basal  plane  c  when  it  truncates  the  top  of  a  rhombohedron  is  an 
equilateral  triangle  (Fig.  223). 

Calcite  (Figs.  -218  to  233).— Axis  c  =  0.854.  Angles  r  A  r  =  74° 
55'  and  c  A  r  =  44°  36^'.  This  mineral  presents  a  greater  variety 
of  habits  than  almost  any  other.  Of  the  rhombohedral  type  the 
negative  rhombohedrons  e  (0112)  and  f  (0221)  and  the  positive 
rhombohedron  r  (1011)  are  the  commonest.  The  angles  of  the  neg- 


RHOMBOHEDRAL   GROUP. 


193 


ative  rhombohedron  7i  (0332)  are  91°  42';  lience  this  form,  when 
it    occurs    without    modifications,    closely    resembles    a    cube. 


FIG.  218. 


FIG.  222. 


FIG.   226. 


FIG.  219. 


FIG.  220. 


FIG.  221. 


m 

....ml 

FIG.  223. 


FIG.  224. 


FIG.  225. 


FIG.  227. 


FIG.  230.  FIG.  231.  FIG.  232.  FIG.   233. 

Fig.  222  is  a  combination  of  the  two  rhombohedrons  r  and  f. 
Figs.  223  and  224  are  combinations  of  the  acute  rhombohedrons 
M  (4041)  and  p  (16.0.16.1)  with  the  base  c.  The  last  figure  bears  a 
close  resemblance  to  the  combination  of  the  prism  m  of  the  first 
order  and  base  c  (Fig  225).  A  prismatic  type  is  common,  the  prism 


194 


HEXAGONAL   SYSTEM. 


being  either  long  or  short  and  usually  of  the  first  order,  m  (1010). 
The  prisms  are  terminated  by  the  base  c,  by  rhombohedrons, 
most  often  e  (Fig.  226),  and  by  scalenohedrons  (Figs.  232  and  233). 
The  scalenohedron  most  often  observed  is  v  (2131)  (Figs.  229  to 
233).  The  twinning-plane  of  Fig.  227  is  r  (0111),  and  the  vertical 
axes  are  inclined  nearly  90°  to  one  another.  Fig.  230  is  a  twinned 
scalenohedron  with  the  base  as  the  twinning-plane. 

Corundum  (Figs.  234  to  236).— Axis  c  =  1.363.    Angles  r  A  r  = 
93°  56'  and  c  A  r  —  57°  34'.     Crystals  of  this  mineral  usually  show 


FIG.  234.  FIG.  235.  FIG.  236. 

the  prism  and  pyramid  of  the  second  order,  a  (1120)  and  n  (2243), 
in  combination  with  the  base  c  (0001)  and  rhombohedron  r  (1011). 

Hematite  (Figs.  237  to  241).— Axis  c  =  1.366.  Angles  r  A  r  = 
94°  0'  and  c  A  r  =  57°  37'.  The  rhombohedron  r  (1011)  (Fig.  237)  oc- 
casionally occurs  without  modification  and  resembles  a  cube,  since 
its  angles  are  near  90°.  Crystals  usually  show  combinations  of  the 


FIG.  237. 


FIG.  238. 


FIG.  239. 


FIG.  240.  FIG.  241. 

rhombohedron  r  with  the  base  c  and  a  pyramid  of  the  second  order, 
n  (2243).  Very  flat  crystals  (scales)  are  common  with  the  basal 
plane  c  or  flat  rhombohedrons  u  (1014)  or  x  (0.1.1.12)  prominent. 


RHOMBOHEDRAL   GROUP. 


195 


Chabazite  (Figs.  242  and  243).— Axis  c  =  1.086.  Angles  r  A  r  = 
85°  14'.  The  common  form  is  the  rhombohedron  r  (1011),  which 
closely  resembles  a  cube.  Fig.  242  represents  this  form  in  com- 
bination with  the  negative  rhombohedrons  e  (0112)  and./  (0221). 


FIG.  242.  FIG.  243. 

Fig.  243  is  a  basal  projection  of  Fig.  242  and  shows  the  symmetri- 
cal development  of  the  rhombohedral  faces  r,  e,  and/*  about  the 
vertical  axis. 

RHOMBOHEDRAL  FOEMS    OF   LOWER   SYMMETRY  THAN  THAT 
PRESENTED   BY   THE  NORMAL  TYPE. 

HemimorpMc  Group. — Tourmaline  Type. 

The  crystals  of  this  group  are  characterized  by  having  a  vertical 
axis  of  trigonal  symmetry  and  three  vertical  planes  of  symmetry. 

It  is  characteristic  of  crystals  of  this  group  that  the  faces  at 
opposite  extremities  of  the  vertical  axis  are  not  alike.  The  forms 
occur  on  tourmaline  (Figs.  244  to  247). — Axis  c  =  0.448.  Angles 
r  A  r  =  46°  62'  and  c  A  r  =  27°  20'.  The.  crystals  of  this  mineral 


FIG.  244.  FIG.  245.  FIG.  246.  FIG.  247. 

usually  present  the  combination  of  the  triangular  prism  m  (1010) 
and  the  hexagonal  prism  of  the  second  order  a  (11^0),  which  are 
terminated  above  by  the  forms  r  (1011),  o  (0221),  and  occasionally 
u  (3251),  and  below  by  r  (Olli),  o  (2021),  and  c  (0001). 


196 


HEXAGONAL   SYSTEM. 


TrirTiomboJiedral  Group. — Phenacite  Type. 

The  crystals  of  this  group  are  characterized  by  having  a  verti- 
cal axis  of  trigonal  symmetry  and  a  center  of  symmetry,  but 
no  planes  of  symmetry. 

The  forms  which  are  especially  characteristic  are  hexagonal 
prisms,  usually  a  (1150),  and  rhombohedrons  of  the  first,  second, 
and  third  orders.  The  three  kinds  of  rhombohedrons  correspond 
in  their  axial  relations  to  one  half  of  the  faces  of  the  hexagonal 
pyramids  of  the  first  and  second  orders  (Figs.  191  and  192),  and  to 
one  quarter  of  the  faces  of  the  dihexagonal  pyramid  (Fig.  193). 

Phenacite  (Fig.  248). — Axis  c  =  0.661.  The  figure  represents  a 
prism  of  the  second  order  a  (1130),  in  combination  with  a  rhombo- 
hedron  of  the  third  order  x  (2132;. 


FIG.  248.  FIG.  349. 

Willemite  (Fig.  249). — Axis  c  =  0.677.  Here  the  prism  of  the 
second  order  a  is  in  combination  with  two  rhombohedrons  of  the 
first  order,  r  (1011)  and  e  (0112),  and  a  rhombohedron  of  the  second 
order  u  (2113). 

Dioptase  (Figs.  250  and  251).— Axis  c  =  0.534.  The  figures  rep- 
resent combinations  of  the  prism  of  the  second  order  a,  with  a 


FIG.  250. 


FIG.  251. 


FIG.  252. 


rhombohedron  of  the  first  order  s  (02S1),  and  of  the  third  order 
X  (1341). 


TRAPEZOHEDRAL    GROUP 


197 


Ilmenite  (Fig.  252). — Axis  c  =  1.385.  The  figure  presents  a 
combination  of  a  rhombohedron  of  the  first  order  r  (1011),  and 
one  of  the  second  order  n  (2243),  with  the  base  c  (0001). 

Trapezohedral  Group. — Quartz  Type. 

The  crystals  of  this  group  are  characterized  by  having  a  vertical 
axis  of  trigonal  symmetry  and  three  horizontal  axes  of  binary 
symmetry  (Fig.  214),  but  no  planes  of  symmetry. 

Quartz  (Figs.  253  to  264).— Axis  c  =  1.100.  Angles  r  A  r  = 
85°  46',  r  A  z  =  46°  16'  and  r  A  m  =  38°  13'.  The  forms  which 
generally  occur  are  the  prism  of  the  first  order  m  (1010),  and  the 
positive  and  negative  rhombohedrons,  r  (1011)  and  z  (0111),  often 
with  the  two  last  forms  about  equally  developed  (Figs.  253  and 
254).  An  unequal  development  of  these  rhombohedrons  (Fig. 
255)  is  also  common.  Although  not  indicated  by  their  simple 


FIG.  253.  FIG.  254.  FIG.  255.  FIG.  256.  FIG.  257. 

combinations,  quartz  crystals  have  a  peculiar  right  or  left 
symmetry.  This  is  shown  by  the  development  of  the  form 
x  (5161),  on  the  right-handed  crystal  (Fig.  256),  and  x  (6151)  on  the 
left-handed  crystal  (Fig.  257).  The  form  which  the  six  x  faces  of 
one  of  these  crystals  would  produce  is  known  as  a  trapezohedron. 
Its  faces  correspond  in  their  axial  relation  to  one  quarter  of  the  faces 
of  the  dihexagonal  pyramid  (Fig.  193).  The  right-  and  left- 
handed  trapezohedrons  having  the  symbols  (2131)  and  (3151)  are 
shown  by  Figs.  258  and  259.  These  forms,  like  the  right  and  left 
hand,  are  symmetrical  with  reference  to  a  plane  passed  between 
them,  but  cannot  by  any  turning  be  made  to  occupy  the  same 
position.  .  In  this  group  the  form  s  (1121)  (Fig.  256)  develops  as 
a  triangular  pyramid  (Fig.  260),  and  has  the  same  symbol  as  a 


198 


HEXAGONAL    SYSTEM. 


pyramid  of  the  second  order  of  the  normal  group  (Fig.  192).  Pos 
itive  and  negative  acute  rhombohedrons,  M  (3031)  and  Ml  (0331) 
(Figs.  261  and  262),  often  occur. 

Twin  crystals  are  very  common,  and  are  of  a  peculiar  character. 


FIG.  258.  FIG.  259.  FIG.  260. 

The  twinning-plane  is  usually  the  prism  of  the  first  order  m,  so 
that  the  positive  rhombohedron  r  of  the  crystal  in  the  normal 
position  coincides  with  the  negative  rhombohedron  z  of  the  crystal 
in  the  twinned  position.  The  parts  of  the  individual  in  the  normal 
and  twin  position  interpenetrate  in  a  very  irregular  manner  (Fig. 
262),  and  the  twin  character  of  the  crystal  is  not  usually  revealed 
by  its  external  form.  Often,  however,  the  faces  of  either  the  posi- 
tive or  negative  rhombohedrons  are  somewhat  corroded  (etched) 
(Fig.  262),  and  then  the  irregular  lines  of  penetration  between  the 
r  and  z  and  the  M  and  Ml  faces  can  be  distinctly  traced. 


FIG.  261.  FIG.  262.  FIG.  263.  FIG.  264. 

Judging  from  the  outward  form  alone,  quartz  crystals  like 
253  and  254  would  appear  to  have  the  same  symmetry  as  crystals 


ORTHORHOMBIC   SYSTEM. 


199 


of  the  normal  hexagonal  type.  This,  however,  is  not  the  case,  for 
if  quartz  crystals  are  subjected  to  the  action  of  hydrofluoric  acid 
artificial  faces  (corrosion  or  etching  faces)  are  developed,  which 
have  a  right-  or  left-handed  distribution  (Figs.  263  and  264),  corre- 
sponding to  that  of  the  x  faces  on  Figs.  256  and  257. 

OKTHORHOMBIC  SYSTEM. 

In  tMs  system  the  forms  are  referred  to  three  axes  a,  b,  and  c 
at  rigJit  angles  to  one  another  and  of  unequal  lengths  (Fig.  265). 
Any  one  of  these  may  be  chosen  for  the  vertical  axes  c ;  the 
longer  of  the  horizontal  ones  is  then  taken  as  b  and  is  called  the 
macro-axis;  the  shorter,  as  a  and  is  called  the  br  achy -axis. 
For  each  substance  crystallizing  in  the  system  the  ratio  lengths  of 
the  axes  must  be  determined  from  the  measurement  of  appropriate 
angles.  In  sulphur,  for  example,  the  axial  ratio  is  a :  b :  c  = 
0.813  :  1 :  1.903  (see  p.  159). 


-c' 
FIG.  265. 


FIG.  266. 


FIG.  267. 


Forms  of  the  Normal  Group. — Bar  lie  Type. 

The  crystals  of  this  group  are  characterized  by  having  three 
axes  of  binary  symmetry  (Fig.  266)  and  three  axial  planes  of  sym- 
metry (Fig.  267). 

The  forms  are  of  three  kinds,  as  follows :  pyramidal,  when 
tne  faces  intersect  the  three  axes ;  prismatic,  when  the  faces 


200 


OKTHORHOMBIC   SYSTEM. 


intersect  two  axes  and  are  parallel  to  the  third  ;  and  pinacoidal, 

when  the  faces  intersect  one  axis  and  are  parallel  to  the   other 

two. 

Pyramids. — These  consist  of  eight  similar  faces,  and  the  form 
with  the  simplest  symbol,  p  (111)  (Fig.  268),  is  called 
the  unit  pyramid.  In  sulphur  (Fig.  281)  the  form 
p  (111)  is  shown  in  combination  with  a  flatter 
pyramid  s  (113).  Thus  it  will  be  noticed  that  on 
the  same  crystal  there  may  be  different  pyramids, 
but  under  no  condition  can  there  be  more  than  eight 
faces  of  the  same  kind. 

Prisms.  —  These    consist  of  four  similar  faces, 
parallel    to    an'  axis;    three    kinds    being    possible, 

according  as  the  faces  are  parallel  to  the  c,  the  b,  or  the  a  axes. 


FIG.  268. 


Fro.  269. 


FIG.  270. 


FIG.  271. 


Vertical  Prisms. — A  prominent  prism  on  a  crystal  is  commonly 
assumed  to  be  the  form  m  (110),  which  is  known  as  the  unit 
prism  (Fig.  269).  This  form  is  a  right  rhombic  prism,  its  four 
faces  being  at  right  angles  to  the  terminal  face  c,  but  never  at 
right  angles  to  one  another,  since  the  a  and .  b  axes  are  not  of 
equal  length. 

Besides  the  unit  prism,  others  may  occur  whose  faces  have 
such  inclinations  that  they  go  from  a  to  a  multiple  of  b,  or  from  b 
to  a  multiple  of  a,  and  are  parallel  to  c.  One  of  these  is  illustrated 
by  topaz  (Figs.  289  to  293),  in  which  I  is  the  prism  (120). 

Horizontal  Prisms,  or  Domes. — When  the  prismatic  forms 
are  parallel  to  the  horizontal  axes  they  are  conveniently  desig- 
nated as  domes.  Fig.  270  represents  the  form  (101),  known  as 


COMBINATIONS, 


201 


the  macro-dome,  because  it  is  parallel  to  tlie  macro-axis  b  and 
Fig.  271,  the  form  (Oil),  called  the  br  achy -dome,  because  it  is 
parallel  to  the  brachy-axis  a.  Each  of  the  ^macro-  and  brachy- 
domes  has  four  similar  faces.  Domes  are  common  forms  which, 
on  crystals  illustrating  combinations  in  this  system,  will  often 
appear  at  one  of  the  extremities  as  a  pair  of  similar  faces.  For 
example,  the  two  triangular  faces  r  at  the-  extremity  of  Fig.  298 
are  planes  of  the  macro-dome  (101).  In, many  instances  the  domes 
intercept  the  vertical  axis  at  a  multiple,  or  fraction,  of  its  unit 
length,  as  illustrated  by  topaz  (Figs.  290  to  293),  in  which  the 
brachy-domes/and  y  have  the  symbols  (021)  and  (041)  respectively. 

Pinacoids. — Three  pinacoids  are  possible,  each 
consisting  cf  two,  similar,  parallel  faces.  These 
forms,  represented  in  Fig.  272,  are  the  macro- 
pinacoid  a  (100),  the  brachy-pinacoid  b  (010),  and 
the  base  or  basal  pinacoid  c  (001).  The  faces  of 
these  three  forms  are  at  right  angles  to  one  another. 

Combinations. — Thje  following  examples  will 
illustrate  the  great  variety  of  habits  which  may 
result  from  the  combinations  of  pinacoids,  prisms,  domes,  and 
pyramids.  It  should  be  noticed  that  the  forms  with  simple  indices, 
a  (100),  b  (010),  c  (001),  m  (110),  and  p  (111),  are  prominent. 
The  position  in  which  the  crystals  are  placed  (the  crystallographic 
orientation)  is  to  a  certain  extent  arbitrary,  since  any  one  of  the 
axes  of  symmetry  may  be  taken  for  the  vertical  axis  c. 

Barite  (Figs.  273  to  277).— Axes  a  :  b  :  c  =  0.815  : 1  : 1.314.     An. 


-*# 

100 


010 


FIG.  272. 


FIG.  276.  FIG.  277. 

gles  m  A  m  —  78°  22'  and  c  A  o  =  52°  43'.     The  crystals  commonly 
have  the  basal  plane  c  prominent  and  are,  therefore,  tabular.    The 


202 


ORTHORHOMBIC    SYSTEM. 


prism  m  (110),  the  macro-dome  d  (102),  and  the  brachy-dome  o 
(Oil)  are  generally  present. 

Celestite  (Figs.  278  and  279).— Axes  a  :  b  :  c  =  0.779  :  1  :  1.280. 
Angles  m  A  m  =  75°  50'  and  c  A  o  —  52°  0'.  The  crystals  are  often 
tabular  like  Figs.  273  to  275  of  barite,  and  often  they  are 
lengthened  out  in  the  direction  of  brachy-axis,  having  the 
brachy-dome  o  (Oil)  prominent  (Fig.  279).  The  prism  m  (110)  and 


FIG.  278. 


FIG.  279. 


the  macro-dome  d  (102)  are  generally  present,  while  Z  (104)  occurs 
occasionally  (Fig.  278). 


FIG.  280. 


FIG.  281. 


FIG.  282. 


Sulphur  (Figs.  280  to  282).— Axes  a  :  b  :  c  =  0.813  : 1  :  1.903. 
Angles  mf\m  —  78°  14'  and  c/\n  =  62°  17'.  A  pyramidal  habit, 
p  (111),  is  common,  often  with  the  apex  truncated  by  the  pyramid 
s  (113)  or  the  base  c.  The  brachy-dome  n  (Oil)  is  also  often 
present. 

Stibnite  (Figs.  283  and284).— Axes  a  :b  :c  =  0.992  :  1  :  1.018. 
Angles  mAm^89°34r  and  c/\p  —  55°  19'.  The  crystals  are 
prismatic,  with  the  prism  m  (110)  and  the  brachy-pinacoid  b  (010) 


COMBINATIONS. 


203 


prominent.     They  are  often  long  and  slender,  and  are  generally 
terminated  by  the  pyramidal  forms  p  (111),  s  (113),  and  r  (343). 


FIG.  283. 


FIG.  284. 


Arsenopyrite(F\g&.  285 and286).— Axes  a  :  b  :  c  =  0.677  : 1 : 1 .188. 
Angles  m  A  m  =  68°  13'  and  cA  q  —  49°  55'.  A  short  prism  m 
(110),  terminated  by  the  brachy-dome  u  (014),  is  the  common 
habit.  The  brachy-dome  q  (Oil)  terminating  the  prism  is  occa- 
sionally met  with. 


FIG.  286. 


FIG.  285. 

CTialcoclte  (Figs.  287  and  288).— Axes  a  :  b  :c  =  0.582  : 1 :  0.970. 
Angles  ml\m  =  60°  25'  and  c  A  d  =  62°  44r.  The  crystals  are  com- 
monly flat,  with  a  striated  basal  plane  c  (001)  and  the  brachy-dome 


FIG.  287. 


FIG.  288. 


d  (021)  prominent.     The   prism   (110),  two  pyramids^?  (HI)  and 
v  (112),  and  the  brachy-pinacoid  b  (010)  are  common  forms.    Twin 


204 


ORTHORHOMBIC    SYSTEM. 


crystals  are  very  common,   and  frequently  imitate  forms  of  the 
hexagonal  system,  as  will  be  explained  under  aragonite  (p.  206). 

Topaz  (Figs.  289  to  293).  —  Axes  a  :  b  :  c  =  0.528  : 1  :  0.477. 
Angles  m  A  m  —  55°  43'  and  c  f\p  =  45°  35'.  The  crystals  are  gen- 
erally prismatic,  with  two  prisms  developed,  m  (110)  and  Z(120). 


FIG.  289. 


FIG.  290. 


FIG.  291. 


FIG.  292. 


FIG.  293. 


The  forms  which  usually  occur  at  the  terminations  are  the  base  cl, 
the  brachy-domes  /  (021)  and  y  (041),  the  macro-dome  d  (201),  and 
the  pyramids  o  (221),  p  (111),  and  i  (223).  Doubly  terminated 
«rystals  are  rather  exceptional. 

Chrysolite  (Figs.   294  to  296).— Axes  a  :  b  :  c  =  0.466  :  1  :  0.586. 
Angles  m  f\m  —  49°  57'  and  c  A  p  —  54°  15'.     In  the  vertical  zone 


FIG.  294. 


FIG.  295. 


FIG.  296. 


the  pinacoids  a  (100)  and  b  (010)  and  the  prism  m  (110)  are  usually 
present,  and  occasionally,  also,  a  second  prism  s  (120).   The  crystals 


COMBINATIONS. 


205 


are  terminated  by  the  brachy-dome  7c  (021),  the  macro-dome  d  (101), 
the  pyramid  p  (III),  and  occasionally,  the  basal  plane  c  (001). 
Fig.  296  is  a  basal  projection  of  Fig.  295,  which  shows  the  sym- 
metrical development  of  the  orthorhombic  forms  when  viewed  in 
the  direction  of  the  vertical  axis. 

Staurolite  (Figs.  297  to  300).— Axes  a  :  b  :  c  =  0.473  : 1  :  0.683. 
Angle  m  A  in  =  50°  40'.  The  crystals  are  generally  prismatic,  with 
the  prism  m  (110)  and  the  brachy-pinacoid  b  (010)  developed. 


m 


\)tl 


FIG.  297. 


FIG.  298. 


FIG.  299. 


FIG.  300. 


They  are  terminated  either  by  the  base  c  (001),  or  a  combination, 
of  c  and  the  macro-dome  r  (101).  Penetration  twins  are  very  com- 
mon; the  prisms  crossing  either  at  nearly  90°  when  a  brachy-dome 
(032)  is  the  twinning-plane,  or  at  nearly  60°  when  a  pyramid  (332) 
is  the  twinning-plane. 

Aragonite  (Figs.    301  to  307).— Axes  a  :  b  :  c  =  0.662  : 1  :  0.721. 
Angles  m  A  m  =  63°  48'  and  c  A  k  =  35°  4T.     Slender,  needle-like 


m 


FIG.  301. 


\ 


FIG.  302. 


\ 


FIG.  303. 


FIG.  304. 


crystals,  either  tapering  to  a  point  or  with    well-defined  faces 
(usually  the  brachy-dome  ~k  (Oil) )  at  the  extremity,  are  common 


206 


ORTHORHOMBIC   SYSTEM. 


(Fig.  301).  The  indices  of  the  steep  pyramid  i  (661)  and  the  brachy- 
dome  j  (0.12.1)  are  uncertain.  Simple  crystals  (Fig.  302)  show- 
ing the  combination  of  the  prism  m,  the  brachy-pinacoid  £,  and 
the  brachy-dome  ~k  are  exceptional ;  while  twins  (Fig.  303), 
often  polys ynthetic  (Fig.  304),  are  more  often  observed,  the  prism 
m  (110)  being  the  twinning-plane.  A  complex  method  of  twinning 
and  intergrowth  is  common,  from  which  a  form  resembling  a  hex- 
agonal prism  results.  The  character  of  these  apparently  hexagonal 
crystals  may  be  explained  as  follows  :  The  cross-section  of  a  sim- 
ple crystal  like  Fig.  302  is  represented  by  Fig.  305.  Three  indi- 


^X^' 

ms^^m 

ilj 

^^^^ 
FIG.  305. 


FIG.  306. 


FIG.  307. 


viduals  I,  II,  and  III  (Fig.  306),  each  striated  parallel  to  the  brachy- 
axis,  and  crystallizing  with  their  prismatic  faces  m  as  the  twin- 
ning-planes,  would  diverge  at  angles  of  about  120°.  Provided 
that  each  crystal  penetrated  beyond  the  center,  a  six-sided  form 
would  result,  with  the  individuals  meeting  along  the  somewhat 
irregular  lines  of  interpenetration  (Fig.  307).  The  complex  charac- 
ter of  such  twins  is  generally  revealed  by  striations  on  the  basal 
planes,  diverging  as  represented  in  Fig.  307,  and  also  by  small  re- 
entrant angles. 

There  is  a  tendency  in  a  number  of  minerals  having  a,  prismatic 
angle  of  nearly  60°,  to  occur  in  complex  twin  crys- 
tals like  those  of  aragonite,  which  imitate  forms  of 
the  hexagonal  system. 

Cerussite  (Fig.  308).— Axes  a  :  t> :  c=0.610 : 1 :  0.723. 
Angle    m  A  m  =  62°    46'.      The    figure    represents 
a  form  with  deep  re-entrant  angles,  resulting  from 
FIG.  308.        the  penetration  of  three  individuals  in  twin  posi- 
tion.    (Compare  Figs.  306   and  307  of   aragonite.)     Each  crys- 


SPHEROIDAL    GROUP. 


sor 


tal  has  the  brachy-pinacoid  b  (010)  prominent,  in  combination 
with  the  prism  m  (110)  and  the  pyramid  p  (111).  Occasion- 
ally twin  crystals  of  cerussite  occur  without  the  re- 
entrant angles,  when  they  may  appear  like  a  com- 
bination of  the  pyramid  and  prism  of  the  hexagonal 
system. 

Cliildrenite  (Fig.  309).— Axes  a\l\c  =  0.778  : 1 :  0.526. 
Angle    m  A  m  —  75°  46'.      This  example  has    been   in- 
troduced to  illustrate  the  combination  of  a  pyramid    FIG.  309. 
s  (121)  in  combination  with  the  pinacoids  a  (100)  and  &  (010). 


ORTHORHOMBIC    FORMS     OF     LOWER    SYMMETRY     THAN"    THAT 
PRESENTED   BY    THE   NORMAL   GROUP. 

HemimorpJiic  Group. — Calamine  Type. 

The  crystals  of  this  group  are  characterized  by  having  one 
axis   of  binary   symmetry  and  two  planes  of  symmetry.      The 
peculiarity  of  the  crystals  is  that  the  forms  at  oppo- 
site extremities  of   the  axis  of  symmetry  are    not 
alike. 

Calamine  (Fig.  310).— Axes  a :  t> :  c  =  0.783  : 1 : 0.478. 
Angle  m  A  m  =  76°  9'.  The  combination  of  the 
macro-pinacoid  a  (100),  the  brachy-pinacoid  ~b  (010), 
and  the  prism  m  (110),  is  terminated  above  by  the 
base  c  (001)  and  the  brachy-  and  macro-domes  i  (031)  and  t  (301), 
while  below  the  pyramid  v  (121)  occurs. 

Sphenoidal  Group. — Up  somite  Type.       /V__?./  \ 

Crystals  of  this  group  are  characterized  by  hav- 
ing three  axes  of  binary  symmetry  and  no  planes  of 
symmetry. 

Epsomite  (Fig.  311).— Axes  a :  b  :  c=0.990  : 1 :  0.571.        FIG.  311. 
Angle  m  A  m  =  89°  26'.    The  figure  represents  the  prism  m  (110), 


FIG.  310. 


208 


MONOCLINIC    SYSTEM. 


terminated  above  and  below  by  two  faces  of  the  form  z,  having 
the  symbol  (111).  The  four  z  faces  alone  produce  a  form  known 
as  a  sphenoid,  similar  to  Fig.  65,  p.  164.  The  faces  correspond 
in  their  axial  relations  to  the  alternating  planes  of  the  ortho- 
rhombic  pyramid  (111)  of  the  normal  group. 

MOJSTOCLINIC  SYSTEM. 

In  this  system  the  forms  are  referred  to  three  axes,  a,  b  and 
c  of  unequal  lengths,  with  a  and  c  intersecting  at  an  acute  angle 
fi  behind,  while  b  is  at  right  angles  to  a  and  c  (Fig.  312).  The 
axis  b  is  called  the  ortho-axis,  because  it  is  at  right  angles  to 
the  other  two ;  and  a  is  called  the  clino-axis,  because  it  is  in- 
clined to  the  vertical  axis  c.  For  each  substance  crystallizing  in 
this  system  the  ratio  lengths  of  the  axes  and  the  axial  inclina- 
tion ft  must  be  determined  from  the  measurement  of  appropriate 
angles.  For  gypsum  the  axial  relation  is  a  :  b  :  c  =  0.690  : 1  :  0.412  ; 
fi  =  80°  42'. 

Forms  of  the  Normal  Group. — Gypsum  Type. 

The  crystals  of  this  group  are  characterized  by  having  one  axis 
of  binary  symmetry  (Fig.  313),  which  is  always  taken  as  the  crys- 
tallographic  axis  b,  and  one  plane  of  symmetry.  The  plane  of 


FIG.  312.  FIG.  313.  FIG.  314. 

symmetry  (Fig.  314)  is  always  supposed  to  occupy  a  vertical  posi- 
tion, and  the  a  and  c  axes  are  located  in  it. 

Monoclinic  forms  are  of  two  kinds ;  either  prismatic  with  four 
similar  faces,  or  pinacoidal  with  two  parallel  faces.     It  is  con- 


NORMAL   GROUP. 


209 


venient,  however,  to  designate  the  forms  according  to  their  rela- 
tion on  the  axes  :  as  pyramids,  when  the  faces  intersect  all  three 
axes  ;  prisms  or  domes,  when  they  intersect  two  axes  and  are 
parallel  to  one  ;  and  pinacoids,  when  they  intersect  one  axis  and 
are  parallel  to  the  other  two. 

Pyramids. — The  form  (111)  (Fig.  315)  consists  of  four  similar 
faces.  These  four  faces  really  constitute  a  prism  with  its  edges 
parallel  to  the  direction  a  :  c.  The  name  pyramid  is  simply  one  of 
convenience  for  designating  the  particular  kind  of  form  which  in- 
tersects the  three  axes.  A  somewhat  similar,  but  different,  and  en- 
tirely independent  form  is  (111)  (Fig.  316),  also  consisting  of  four 


FIG.  315.  FIG.  316.  FIG.  317. 

similar  faces.  The  solid  represented  by  Fig.  317  is  a  combination 
of  the  two  independent  forms  p  (111)  and  o  (111).  It  should  be 
distinctly  understood  that  no  form  in  this  system  is  more  compli- 
cated than  the  ones  just  explained.  The  symbol  may  be  less  simple, 
for  example  (321),  but  the  symmetry  demands  the  existence  of  only 
four  faces  of  the  same  kind. 

Prisms. — A  prismatic  form,  consisting  of  four  similar  faces 
is  commonly  taken  as  the  unit-prism  m  (110)  (Fig.  318),     Such  a 


FIG.  318.  FIG.  319.  FIG.  320. 

form  is  an  inclined  prism,  the  two  faces  in  front  making  equal 
angles  with  the  terminal  face  c,  but  not  angles  of  90°.    Besides 


210  MONOCLINIC    SYSTEM. 

the  prism  (110)  others  occur,  whose  faces  are  so  inclined  that  they 
go  from  a  to  a  multiple  of  &,  or  from  b  to  a  multiple  of  a,  and 
are  parallel  to  c.  Two  prisms,  m  (110)  and  z  (130),  often  occur  on 
orthoclase  (Fig.  328). 

Domes. — The  form  (Oil)  (Fig.  319)  has  four  similar  faces 
which  make  an  inclined  prism.  It  is  convenient  to  designate  this 
form,  however,  as  a  clino-dome,  so  named  because  the  faces  are 
parallel  to  the  clino-axis  a. 

Owing  to  the  symmetry  of  monoclinic  crystals  the  form  (101) 
occurs  as  a  pair  of  similar  faces.  Fig.  320  represents  two  inde- 
pendent forms  (101)  and  (101),  called  ortho-domes,  in  combination 
with  a  terminal  face  b. 

Pinacoids. — There  are    three  forms,    each    consisting  of    two 
parallel  faces  (Fig.   321),   which    are    especially 
important :   the  ortTio-pinacoid  a  (100),  the  clino- 
pinacoid  b  (010),  and  the  base  or  basal  pinacoid 
c  (001).     The  clino-pinacoid  &,  which  is  parallel  to 
the  symmetry  plane  (Fig.  313),  is  at  right  angles 
to  both   the   base  c  and    the  ortho-pinacoid  a, 
FIG.  321.          while  the  two  latter  forms  make  an  angle  with 
one  another  which  is  equal  to  the  axial  inclination  fi. 

Combinations. — The  following  examples  will  illustrate  some  of 
the  various  habits  which  may  result  from  the  combination  of  mon- 
oclinic forms,  and  it  should  be  noticed  that  it  is  possible  in  almost 
all  cases,  to  orientate  the  crystals  so  that-  the  symbols  of  their* 
forms  can  be  expressed  by  very  simple  indices.  The  prevailing 
forms  are  the  pinacoids  a  (100),  b  (010),  and  c  (001),  the  prism 
m  (110),  and  the  pyramid^  (111). 

Gypsum  (Figs.  322  to  325).— Axes  a  :  b  :  c  =  0.690  :  1 :  0.412 ; 
$  =  80°  42'.  Angles  m  A  m  =  68°  30'  and^  A  p  =  36°  12'.  Crystals 
usually  have  the  clino-pinacoid  b  (010)  prominent,  in  combination 
with  the  prism  m  (110)  and  the  pyramid  p  (111).  The  ortho-dome 
e  (103)  is  often  present.  Twins  are  common,  with  the  ortho-pina- 
coid (100)  as  the  twinning-plane  (Fig.  325). 

The  arbitrary  method  of  orientating  a  monoclinic  crystal  and 


NORMAL    GROUP. 


211 


naming  the  forms  is  here  brought  to  notice.  The  four  faces  of  the 
so-called  pyramid  p,  if  placed  vertically,  could  have  been  taken  as 
the  prism  (110),  when  the  m  faces  would  most  naturally  be  taken 
as  the  clino-dome  (Oil).  A  crystal  of  gypsum  thus  orientated 


\E/ 

\y 
FIG   323.  FIG.  323.  FIG.  324.  FIG.  325. 

would,  of  course,  have  a  different  axial  ratio  than  the  one  given 
above.  The  only  form  on  monoclinic  crystals  which  is  actually 
determined  by  the  symmetry  is  the  clino-pinacoid  b  (010). 

OrtJioclase  (Figs.  826  to  329).—  Axes  a:b:c=  0.658  : 1 : 0.555  ; 
ft  =  63°  57'.  Angles  m  A  m  =  61°  13',  c  A  x  =  50°  16',  and  c  A  y  = 
80°  18'.  The  prominent  forms  are  the  prism  m  (110)  and  the  pina- 


FIG.  326.  FIG.  327.  FIG.  328.  FIG.  329. 

coids  b  (010)  and  c  (001).  A  second  prism  z  .(130),  the  ortho-domes 
x  (101)  and  y  (201),  and  the  pyramid  o  (111),  are  often  present.  A 
common  kind  of  twinning  consists  of  two  individuals  united  with 
their  b  faces  in  common  (Fig.  329).  The  twinning- axis  is  the  ver- 
tical axis  c.  On  the  crystal  in  the  normal  position  the  base  c 
slopes  toward  the  front,  while  in  the  twinned  individual  it  slopes 
toward  the  back. 

Pyroxene  (Figs.   330  to  336).— Axes  a:b:c=  1.092  :  1 :  0.589  ; 
ft  =  74°  10'.     Angles  m  A  m  =  92°  50',  p  A  p  =  48°  29',  and  s  A  s  = 


212 


MONOCLINIC   SYSTEM. 


59°  11'.  Prismatic  crystals  are  common,  the  prisms  m  (110)  being 
stout,  nearly  rectangular  (m  A  m  =  92°  50'),  and  generally  truncated 
by  the  ortho-pinacoid  a  (100)  and  the  clino-pinacoid  b  (010).  The 
crystals  are  variously  termipated ;  the  prevailing  forms  being  the 
base  c  (001),  the  ortho-domes  d  (101)  and  n  (102),  and  the  pyramids 


FIG.  330.  FIG.  331.  FIG.  332.  FIG.  333. 

p'(lll),  v  (221),  s  (111),  and  o  (221).  Fig.  334  is  a  basal  projection 
of  Fig.  333,  and  shows  the  symmetrical  development  of  the  mono- 
clinic  forms  on  either  side  of  the  symmetry  plane,  intersecting  the 


» 


FIG.  334.  FIG.  335.  FIG.  336. 

crystal  parallel  to  the  face  b.  Figs.  335  and  336  represent  the  or- 
dinary development  of  crystals  of  augite,  a  variety  of  pyroxene 
common  in  volcanic  rocks. 

Amphibole  (Figs.  337  to  339).— Axes  a  :  I :  c  =  0.551 : 1 :  0.294  ; 
fi  =  73°  58'.  Angles  m  A  m  =  55°  49'  and  r  A  r  =  31°  32'.  The  crys- 
tals are  commonly  long  and  bladed,  with  the  prism  m  (110)  promi- 
nent, or  apparently  hexagonal  (m  A  m  =  nearly  60°),  when  m  and 
the  clino-pinacoid  b  are  about  equally  developed.  A  second  prism 
e  (130)  and  the  ortho-pinacoid  a  (100)  are  often  present.  The 
crystals  are  generally  terminated  by  the  faces  of  the  clino-dome 
r  (Oil). 


NORMAL   GROUP. 


213 


FIG.  337.  FIG.  338.  FIG.  339. 

Titanite  or  SpTiene  (Figs.  340  to  342). —  Axes  a  :  b  :  c  = 
0.755  : 1 :  0. 854 ;  ft  =  60°  17'.  Angles  m  A  m  =  66°  29',  p  A  p  =  43°  49', 
andc  A  p  =  38°  16'.  The  prism  m  (110)  and  the  pyramid  p  (111) 


FIG.  340.  FIG.  341.  FIG.  342. 

are  generally  prominent,  and  in  combination  with  the  base  c  (001) 
and  the  ortho-pinacoid  a  (100).  The  very  obtuse  interfacial  angles 
of  Fig.  341  are  conspicuous,  from  which  the  name  sphene,  mean- 
ing a  wedge,  is  derived. 

Epidote   (Figs   343   and   344).— Axes  a :  b  :  c  =  1.578  : 1  : 1.804  ; 
ft  =  64°  37'.   Angles  m  A  m  =  109°  66',  n  A  n  =  70°  29',  and  c  A  r  = 


/-..     / 


FIG.  343.  FIG.  344. 

63°  42'.  The  crystals  of  epidote  generally  have  a  somewhat  un- 
usual development,  being  long  in  the  direction  of  the  symmetry, 
axis,  owing  to  the  prominence  of  the  base  c  (001),  the  ortho-pina- 


214  TBICLINIC    SYSTEM. 

coid  a  (100),  and  the  ortho-domes  r  (101)  and  i  (102).  At  the  ends, 
the  pyramid  n  (111)  is  generally  the  most  prominent  form,  while  the 
other  forms  shown  in  Fig.  344  are  the  clino-pinacoid  b,  the  clino- 
domes  o  (Oil)  and  k  (012),  the  prism  m  (110),  and  the  pyramid^?  (111). 

MONOCLINIC  FORMS  OF  LOWER  SYMMETRY  THAN  THAT  PRE- 
SENTED BY  THE  NORMAL  GROUP. 

Two  groups  are  recognized,  but  are,  however,  very  rarely 
observed.  One  is  hemimorpTlic,  having  an  axis  of  binary  symme- 
try but  no  plane  of  symmetry  ;  the  other  has  a  plane  of  symmetry, 
but  no  axis  of  symmetry. 

TRICLINIC  SYSTEM. 

In  this  system  the  forms  are  referred  to  three  axes,  a,  ft,  and 
c,  of  unequal  lengths,  and,  intersecting  at  oblique  angles,  a,  fi, 
and  y  (Fig.  345).  The  directions  which  are  taken  to  represent  the 
axes  correspond  to  prominent  crystallographic 
features,  but  otherwise  are  arbitrarily  chosen. 
Any  one  of  the  axes  may  be  taken  as  the 
vertical  axis  c,  and  of  the  lateral  ones,  b  is 
the  longer  or  macro-axis  and  a  the  shorter  or 
brachy-axis.  For  each  mineral  crystallizing 
in  this  system,  the  ratio  lengths  of  the  axes  and  the  inclinations 
«,  /?,  and  Y  must  be  determined  from  the  measurement  of  appro- 
priate angles.  In  axinite,  for  example,  a:b:c  =  0.492  : 1 :  0.480  ; 
and  a  =  82°  54',  ft  =  91°  52',  and  y  =  131°  32', 

Forms  of  the  Normal  Group.— Axinite  Type. 

Crystals  of  this  group  have  a  center  of  symmetry,  but  neither 
planes  nor  axes  of  symmetry.  Each  form  consists  of  two  sim- 
ilar parallel  faces,  diametrically  disposed  with  reference  to  a 
central  point. 

Each  form,  since  it  consists  of  only  two  parallel  faces,  has  the 
character  of  &pinacoid.  It  is  convenient,  however,  to  designate 
the  forms  according  to  their  relations  on  the  axes,  as  pyramids 
when  they  intersect  the  three  axes,  as  prisms  or  domes  when 


NORMAL   GROUP. 


215 


they  intersect  two  axes  and  are  parallel  either  to  the  vertical  or 
to  one  of  the  horizontal  axes,  and  as  pinacoids  when  they  inter- 
sect one  axis  and  are  parallel  to  the  other  two. 

Pyramids.— The  form  (111)  (Fig.  346)  consists  of  two  similar 
faces,  and  is  designated  as  a  pyramid  for  the  sake  of  convenience. 
Four  entirely  different  forms  are  possible,  each  of  which  intersects 
ti;e  axes  at  their  unit  lengths,  (111),  (111),  (111),  and  (111)  (Fig.  347). 


FIG.  346.  FIG.  347.  FIG.  348. 

single  form  can  be  more  complex  than  the  one  represented  by 
Pig.  346.  The  symbol  may  be  more  complicated,  for  example 
(321),  but  the  form  can  consist  of  but  two  faces. 

Prisms.— The  forms  m  (110)  and  M (110)  (Fig.  348)  each  consists 
of  two  similar  faces,  and  the  four  planes  constitute  a  triclinic 
•prism,  whose  faces  do  not  make  equal  angles  with  the  terminal 
plane  c. 

Domes. — If  the  forms  are  parallel  to  the  5  axis,  for  example, 
(101)  or  (101)  (Fig.  349),  they  are  called  macro-domes-,  and  if  par- 
allel to  the  a  axis,  for  example,  (Oil)  or  (Oil)  (Fig.  350),  they  are 
called  bracJiy -domes. 

Pinacoids.— When  it  is  reasonable  to  do  so,  it  is  customary  to 
select  three  prominent  faces  of  a  crystal  to  represent  the  macro- 


FIG.  349.  FIG.  350.  FIG.  351. 

pinacoid  a  (100),  the  br  achy -pinacoid  b  (010),  and  the  ~base  or 
basal  pinacoid  c  (001)  (Fig.  351).  These  three  forms  are  important, 
because  their  intersections  determine  the  axial  directions. 


216 


TRICLINIC    SYSTEM. 


Combinations.— The  following  illustrations  will  serve  to  show 
some  of  the  variations  in  habit  which  may  result  from  the  combi- 
nation of  triclinic  forms.  Since  the  crystals  have  neither  a  plane 
nor  an  axis  of  symmetry,  any  face  may  be  taken  as  a  pyramid,  prism, 
dome,  or  pinacoid.  In  orientating  a  triclinic  crystal  the  most 
important  thing  to  be  considered  is  the  adoption  of  such  a  position 
that  the  prominent  faces  will  have  as  simple  indices  as  possible. 
It  should  be  noticed,  in  studying  the  examples  given  below,  that 
the  crystals  have  been  so  orientated  that,  in  most  cases,  the  promi- 
nent forms  are  the  pinacoids  a  (100),  b  (010),  and  c  (001),  and  the 
prisms  m  (110)  and  J^~(110),  all  having  very  simple  indices. 

Axinite  (Fig.  352).  —  Axes  a  :  ~b  :  c  =  0.492  :  1  :  0.480  ;  a  = 
82°  54',  ft  =  91°  52',  and  y  ==  131°  32'.  Angles 
a  A  m  =  15°  34',  a  A  M  —  28°  55',  m  A  p  =  30°  33', 
and  M  A  r  =  45°  15'.  Prominent  forms  are  the  two 
prisms  m  (110)  and  M  (110),  terminated  by  the  pyra- 
mids p  (111)  and  r  (111),  and  the  macro-dome  s 
(201).  The  exceptionally  acute  and  obtuse  angles 
of  the  crystal  are  conspicuous,  whence  the  name  axinite  (ASit^ 
an  axe). 

AlUte  (Figs.  353  to  356).— Axes  a:b:c  =  0.633  : 1  :  0.558  ;  a  = 
94°  3',  ft  =  116°  29',  and  y  =  88°  9'.  Angles  b  A  c  =  86°  24',  m  A  c. 
=  65°  18',  M  A  c  =  69°  10',  and  m  A  M  =  59°  14'.  The  crystals  are 


FIG.  352. 


FIG.  353. 


FIG.  354. 


FIG.  355. 


FIG.  356. 


commonly  flat  (tables)  with  the  brachy-pinacoid  l>  (010)  prominent. 
Combined  with  this  are  the  two  prisms  m  (110)  and  Jf(llO),  the 
base  c  (001),  and  the  macro-dome  x  (101).  The  pyramids  o  (111) 
and  q  (111)  are  often  present.  Twins  are  common,  often  polysyn- 


NORMAL    GROUP. 


217 


FIG. 


thetic  (Fig.  356),  the  pinacoid  ~b  being  the  twinning-plane.  The 
basal  planes  of  polysynthetic  crystals  show  a  repetition  of  re- 
entrant and  salient  angles  ;  and  when  the  lamellae  are  numerous, 
as  is  often  the  case,  the  basal  plane,  or  cleavage-surface,  shows  a 
series  of  fine  striations  (Fig.  87,  p.  168).  The  similarity  between 
albite  and  the  closely  related  mineral  orthoclase  of  the  monoclinic 
system  (p.  211),  may  be  seen  by  comparing  their  axial  ratios  and 
interfacial  angles. 

Cyanite  (Fig.  357).— Axes  a  :  I  :  c  =  0.899  :  1  :  0.709  ; 
a  =  90°  5',  ft  =  101°  2',  and  y  =  105°  44'.  Angles  a  A  t> 
=  73°  56',  a  A  c  =  78°  30',  b  A  c  =  86°  45',  and  a  A  M  = 
48°  18'.  The  crystals  are  generally  long  and  bladed, 
owing  to  the  prominence  of  the  macro-pinacoid  a  (100), 
and  are  seldom  terminated  by  distinct  faces. 

Rhodonite,  variety  Fowlerite  (Fig.  358).  —  Axes  a  :  b  :  c  — 
1.078  :  1  :  0.626  ;  a  =  103°  39',  ft  =  108°  48',  and  y  = 
81°  55'.  Angles  c  A  a  =  72°  30',  a  A  m  =  48°  33', 
m  A  M  =  92°  49',  c  A  m  =  68°  26',  and  c  A  Jfcf = 
86°  41'.  The  crystals  are  commonly  somewhat 
tabular,  with  the  base  c  (001)  prominent.  The  two 
prisms  m  (110)  and  J/"(lIO)  are  common,  while  the 
pyramids  n  (221)  and  k  (221)  are  usually  subordinate.  Rhodonite 
(m  A  M  =  92°  49')  is  closely  related  to  pyroxene  (p.  210),  in  which 
m  A  m  =  92°  50'. 

Chalcanthite  (Blue  Vitriol)  (Fig.  359).  —  Axes 
a:b:c  =  0.566  : 1 : 1.055  ;  or  =  82°  21',  ft  =  73°  11',  and 
y  =  77°  37'.  Angles  a  A  b  =  100°  41',  a  Am  =  30°  51', 
a  A  M  =  25°  59',  and  m  /\p  =  52°  20'.  The  crystals 
commonly  have  the  two  pinacoids  a  (100)  and  5  (010) 
and  the  two  prisms  m  (110)  and  M  (110)  prominent, 
and  are  terminated  by  the  faces  of  the  pyramid^?  (111). 


FIG.  358. 


FIG.  359. 


218  THE   THIRTY-TWO   CLASSES   OF    CRYSTALS. 


TEICLINIC    FORMS    OF    LOWER     SYMMETRY    THAN  THAT   PRESENTED 
BY   THE   NORMAL   TYPE. 

Triclinic  crystals  have  been  observed  which  do  not  have  a  centei- 
of  symmetry,  but  no  minerals  belonging  to  this  class  are  known. 
On  the  crystals,  each  form  consists  of  a  single  plane,  but  the 
occurrence  of  any  crystal  face  does  not  necessitate  the  existence 
of  one  parallel  to  it. 

NOTE  CONCERNING  THE  SYSTEMS  OF  CRYSTALLIZATION. 

Although  crystals  are  classified  into  six  systems,  according  to 
their  axial  relations,  each  system  is  subdivided  into  groups  with 
varying  degrees  or  kinds  of  symmetry.  Each  of  these  subdivi- 
sions really  constitutes  a  distinct  class,  characterized  by  &  particu- 
lar kind  of  symmetry,  which  a  substance  crystallizing  in  that  class 
will  invariably  show.  From  purely  mathematical  considerations 
it  can  be  shown  that  there  are  thirty -two  possible  classes  to  which 
crystals  can  be  referred,  and  all  but  three  of  them  have  been  ob- 
served either  among-  minerals  or  artificially  crystallized  salts. 

The  possible  kinds  of  symmetry  are  sn'own  in  the  table  oppo- 
site. The  references  will  serve  to  indicate  the  important  classes 
which  have  been  described  in  the  foregoing  pages. 

•  .  •'.; 

PSEUDOMORPHOUS    CRYSTALS. 

Although  the  occurrence  of  a  mineral  in  distinct  crystals  may 
generally  be  regarded  as  a  proof  of  the  homogeneous  character  and 
purity  of  the  material  (p.  156),  this  is  not  always  the  case.  A  sub- 
stance may  either  undergo  chemical  alteration  or  be  replaced  by 
material  of  entirely  different  character  without  perceptible  change 
in  the  crystalline  form,  and  thus  crystals  result  which  have  the 
form  of  one  mineral  and  the  chemical  composition  of  another. 
Such  crystals  are  known  as  pseudomorphs  (tyevdrfs,  false,  and 
/7,  form). 


THE   THIRTY-TWO    CLASSES    OF    CRYSTALS. 


219 


TABLE    SHOWING    THE    SYMMETRY    OF    THE    THIRTY-TWO    CLASSES   OF 

CRYSTALS. 

An  asterisk  denotes  the  absence  of  a  Center  of  Symmetry. 


Isometric.  System. 

5 

Group. 

Planes  of 
Symmetry. 

Axes  of  Symmetry. 
4)  Hexagonal. 
^  Tetragonal. 
A   Trigonal. 
•   Binary. 

Greatest  Number  of  Similar 
Faces  Possible  on  a  Crystal, 
with  Reference. 

1 

2 
3 
4 
5 

Sormal 
Pyritobedral 
letrabedral* 

K 

9 
3 
6 
0 
0 

3+      4A        6* 
39       4A 
3  *       4  A 
3  +       4  A        6« 
3  *      4  A 

48.   Hexoctabedron,  Fig.  113 
24.  Diploid,  Fig.  118 
24.    Hexakistetrahedron,  F.  138 
24.  Rare,  cuprite 
12.   liare,  langbeinite 

K 

Hexagonal. 

6 

s 

9: 

10  j 

1 

Normal 
Hemimorpbic* 

Tri-pyramidal 
* 

7 
6 
1 
0 
0 

•           o> 

1  * 
1  * 
•        6  • 

24.  Dibexagonal  pyr.,  F.  193 
12.  Rare  (p.  190) 
12.  Tbe  n  faces,  Fig.  207 
12.  Rare,  artificial  salts 
6,  Rare,  nepbelinite 

* 

1  » 

Hexagonal- 
rbombohedral. 

11 
12 
13 
14 

15 

16 

17 

4 
3 
3 
0 

0 

1 
0 

1  A       3  • 

12.   Unknown 
12.  Scalenobedron,  Fig.  217 
6.   Tbe  u  faces,  Fig.  247 
6.   Rbombobedron.     Tbe   0 
faces,  Fig.  248 
6.   Trapezobedron,  Figs. 
258  and  259 
6.   Unknown 
3.   Rare,  artificial  salt 

Normal 
Hemhnorphlc* 
Tri-rbombohedral 

Trapezobedral* 

i  A    y  • 
i  A 
1  A 

1  A      3* 

i  A 
i  A 

•X- 

Tetragonal. 

18 
19 
20 
21 
22 
23 
24 

Normal 
# 

5 

4 

1 
2 
0 
0 
0 

1+      *• 
14- 
i^ 

1  ^       2^ 

1  *       4« 

1  4 
1  ^ 

16.  Di  tetragonal  py  r.  ,  F.  146 
8.  Rare,  artificial  salts 
8.  Tbe  s  faces,  Fig.  173 
8.  Tbe  x  faces,  Fig.  185 
8.  Rare,  artificial  salts 
4.  Rare,  wulfenite 
4.  Unknown 

Tri-pyramidal 
Spbenoidal* 
# 

* 

* 

Ortbo- 
rbombic. 

25 
26 

27 

Normal 
Hemimorpbic* 
Spbenoidal* 

3 
2 

0 

3  • 

1  • 
3  * 

8.  Pyramid,  Fig.  268 
4.  Tbe  i>  faces,  Fig.  310 
4.  Tbe  2  faces,  Fig.  311 

6  o 

§:§ 

s'-z 

1     0 

§1 

o 

28 
29 
30 

Normal 
* 

1 
0 

1 

1  • 

1  «» 
None 

4.  The  p  faces,  Fig.  322 
2.   Rare,  artificial  salts 
2.   Rare,  clinobedrite 

* 

31 
32 

Normal 
# 

0 
0 

None 
None 

2.  Tbe  p  faces,  Fig.  352 
1.  Rare,  artificial  salt 

220  PSEUDOMORPHOUS   CRYSTALS. 

Pseudomorphs  by  Chemical  Alteration  of  the  Original  Material. 
—  Crystals  of  pyrite,  FeS2,  by  long  exposure  may  become  oxidized 
and  hydrated,  and  partly  or  wholly  converted  into  limonite  (iron 
rust),  Fe4O8(OH)6.  Thus  pseudomorphs  of  limonite  after  pyrite 
are  formed.  A  similar  change  takes  place  when  iron  rusts  from 
exposure.  If  a  discarded  rusty  tool  is  found,  the  character  of  the 
implement  may  generally  be  determined  from  the  shape  of  the 
mass  of  iron  rust,  even  though  the  steel  has  wholly  disappeared, 
and  so,  from  the  shape  of  a  pseudomorphous  crystal,  the  nature 
and  name  of  the  original  mineral  may  generally  be  inferred. 
Other  illustrations  are  the  change  by  hydration  and  loss  or  gain 
of  magnesium  oxide,  of  the  silicates  chrysolite,  Mg2SiO4,  and  en- 
statite,  MgSiOs,  to  serpentine,  H4Mg3Si209. 

2MgaSiO4  +  2H2O  less  MgO  =  H4Mg3Si2O9. 
2MgSiO3  +2H,Oplus  MgO  =  H4Mg3Si2O9. 


Pseudomorphs  by  Incrustation  and  Replacement.  —  Often  crys- 
tals of  fluorite  become  coated  with  quartz,  and  subsequently  the 
former  is  removed  by  solution  or  other  agency,  and  the  space 
thus  left  vacant  is  wholly  or  partly  filled  by  a  deposit  of 
quartz,  thus  producing  pseudomorphs  of  quartz  after  fluorite. 
Another  illustration  is  furnished  by  petrified  wood.  As  the  wood 
decays  the  silica  which  is  dissolved  in  the  percolating  water  is  de- 
posited upon  its  fibers,  often  preserving  the  delicate  structure 
of  the  wood  in  a  remarkable  manner. 

Pseudomorphs  Resulting  from  Molecular  Change.  —  When 
molten  sulphur  is  cooled,  rather  quickly,  crystals  belonging  to 
the  monoclinic  system  are  formed,  which  cannot  be  preserved  at 
ordinary  temperatures,  because  they  undergo  a  molecular  change 
to  the  orthorhombic  modification  (p.  202).  Similar  changes  in 
molecular  condition,  without  the  addition  or  removal  of  chemical 
constituents,  take  place  in  nature,  giving  rise  to  pseudomorphs 
of  calcite  after  aragonite,  rutile  after  ~brookite,  amphibole  after 
pyroxene,  etc.  These  are  also  called  paramorpJis. 


STRUCTUEE. 


STRUCTURE  OF  MINERALS. 

In  describing  the  structure  of  minerals  a  number  of  terms  are 
conveniently  employed  which  will  need  a  little  explanation. 

Granular. — When  a  mineral  consists  of  an  aggregate  of  crys- 
talline particles  of  about  the  same  size,  as  marble  and  some  varieties 
of  galena. 

Compact. — Earthy. — A  more  or  less  firm  consistency,  resulting 
from  a  uniform  aggregation  of  exceedingly  minute  particles,  as 
kaolin  (clay). 

Massive. — When  a  substance  exhibits  no  crystal  faces,  although 
:lt  may  possess  a  crystalline  structure.  Massive  materials  (pieces 
of  quartz,  chalcopyrite,  etc.)  are  more  often  encountered  than  well- 
crystallized  specimens. 

Amorphous. — When  no  trace  of  crystalline  structure  exists. 
There  are  not  many  minerals  which  are  truly  amorphous,  and 
they  are  not  always  easily  distinguished  from  massive  materials. 
Opal,  amber,  and  obsidian  (volcanic  glass)  are  good  examples. 

Columnar. — When  there  is  a  parallel,  or  nearly  parallel,  group- 
ing of  prisms  or  columns,  as  illustrated  by  some  varieties  of 
wollastonite  and  beryl. 

Fibrous. — A  structure  similar  to  the  foregoing,  but  in  which 
the  individuals  are  exceedingly 
minute,  as  illustrated  by  some  va- 
rieties of  serpentine  (Fig.  360), 
amphibole  (variety  asbestus),  and 
gypsum.  The  fibers  may  often  be 
separated  or  pulled  apart  into  fine  Fj^ 

Shreds.      Minerals  possessing  a  fine  Fibrous  Structure.— Serpentine. 

fibrous  structure  usually  have  a  silky  luster  ;  hence  fibrous  gypsum 
is  called  satin- spar. 

Foliated. — When  a  mineral  separates  easily  into  plates,  as  in 
some  varieties  of  serpentine  and  brucite. 

Micaceous. — A  structure  similar  to  the  foregoing,  but  in  which 


$22 


STRUCTURE. 


the  material  can  be  split  readily  into  exceedingly  thin  sheets,  as 
muscovite  (common  mica). 

Radiated. — When  columns,  fibers,  or  foliae  diverge  from  cen- 
tral points,  as  in  pectolite  (Fig.  361),  wavellite,  and  pyrophyllite. 

Reniform  and  Mammillary. — These  are  terms  applied  to 
rounded  masses,  usually  with  a  smooth  exterior,  which  have  a  re- 


FIG.  361.  FIG.  362. 

Radiated  Structure.— Pectolite.  Reniform  Structure.—  Kidney-iroii  or 

Hematite. 

semblance  either  to  a  kidney  or  to  mammae.     They  are  illustrated 
by  some  varieties  of  hematite  (Fig.  362)  and  malachite. 

Botryoidal  and  Globular.— These  terms  are  applied  to  rather 
small  rounded  or  spherical  prominences,  found  in  some  varieties  of 
smithsonite  (Fig.  363),  opal  (hyalite)  and  other  minerals. 


FIG.  363. 
Botryoidal  Structure. — Smithsonite. 


FIG.  364. 
Stalactitic  Structure. — Limonite. 


Stalactitic. — When  the  material  occurs  in  pendants  (icicle-like 
forms),  as  limonite  (Fig.  364)  and  some  calcite  (cave-stone).    StalaC' 


CLEAA7AGE.  223 


tites  form  in  cavities.     The  material  is  deposited  generally  from 
dripping  water. 


COHESION  RELATIONS  OF  MINERALS. 

Cleavage. — Crystallized  substances  usually  exhibit  a  tendency 
to  break  more  readily  in  some  directions  than  in  others,  often 
yielding  smooth  surfaces  which  resemble  crystal  faces.  This  prop- 
erty is  known  as  cleavage.  The  directions  of  cleavage  are  always 
parallel  to  possible  crystal  faces,  and  usually  to  faces  with  simple 
indices.  Cleavage  is  a  separation  parallel  to  the  molecular  planes 
composing  the  crystal  (Fig.  51.  p.  157),  and  is  due  to  the  fact  that 
the  forces  which  unite  the  molecules  are  weaker  in  certain  direc- 
tions than  in  others.  Some  substances,  such  as  calcite,  gypsum,  and 
mica,  can  be  cleaved  with  great  ease.  Such  cleavage  is  designated 
as  perfect,  and  if  the  cleavage-fragment  is  held  in  an  appropriate 
position,  close  to  the  eye,  a  perfect  reflection  of  distant  objects  will 
be  obtained  from  its  surface.  In  some  minerals  cleavage  is  poor, 
or  can  only  be  detected  with  difficulty.  In  studying  minerals  the 
ease  with  which  cleavage  can  be  produced  and  its  direction,  or  its 
relation  to  the  crystal  form,  should  be  carefully  noted.  Often  the 
cracks  in  a  crystal  reveal  both  the  presence  and  the  direction  of 
cleavage.  To  produce  a  cleavage,  place  the  edge  of  a  knife-blade 
or  chisel  on  a  crystal  face,  parallel  to  the  direction  in  which  the 
cleavage  is  supposed  to  exist,  and  strike  a  sharp,  quick  blow  with 
a  hammer. 

In  the  isometric  system  cleavage  may  be  cubic  (Fig.  95,  p.  170, 
and  Fig.  365),  as  in  galena  and  halite  ;  octahedral  (Fig.  96,  p.  170), 
as  in  fluorite  ;  or  dodecahedral  (Fig.  97,  p.  170),  as  in  sphalerite. 

In  the  hexagonal  system  cleavage  is  designated  as  basal  or 
prismatic  when  parallel,  respectively,  to  the  faces  lettered  c  or  m 
(Fig.  191,  p.  187).  In  the  rhombohedral  group  it  is  often  rlioinbo- 
Tiedral  (Fig.  219,  p.  193,  and  Fig.  366),  as  in  calcite.  This  is  char- 
acterized by  being  equal  in  three  directions,  but  not  at  right  angles 
to  one  another. 


224  PARTING. 

In  the  remaining  systems  cleavage  is  called  basal  when  it  is 
in  one  direction,  parallel  to  the  terminal  face  c  (001)  in  the  figures 


FIG.  365.  FIG.  366. 

Cubic  Cleavage. — Galena.  Rhombohedral  Cleavage. — Calcite. 

pp.  179  to  217,  illustrated  by  apophyllite  in  the  tetragonal,  topaz 
in  the  orthorhombic,  and  orthoclase  in  the  monoclinic  systems. 
Cleavage  is  called  pinacoidal  when  it  is  in  one  direction,  parallel 
to  the  vertical  pinacoids  of  the  orthorhombic,  monoclinic,  or  tri- 
clinic  systems,  as  in  stibnite  (Fig.  283,  p.  203)  and  gypsum  (Fig. 
322,  p.  211),  where  it  is  parallel  to  the  faces  1)  (010).  In  orthoclase 
(Fig.  326,  p.  211)  there  is  a  perfect  basal  cleavage  parallel  to  c  (001), 
and  a  less  perfect  cleavage  at  right  angles  to  it,  parallel  to  the  clino- 
pinacoid  b  (010).  A  cleavage  is  designated  as  prismatic  when 
produced  with  equal  ease  in  two  directions,  parallel  to  the  faces 
m  (110)  or  a  (100)  of  the  tetragonal  system  (pp.  179  to  183),  or  paral- 
lel to  the  faces  m  (110)  in  the  orthorhombic  and  monoclinic  systems 
(pp.  200  to  213).  Amphibole  furnishes  a  good  example  of  prismatic 
cleavage. 

Parting. — It  is  the  case  in  some  crystals  that  when  they  are 
subjected  to  strain  or  pressure  there  is  apparently  a  slipping  or 
gliding  of  the  particles  along  certain  molecular  planes.  This  is 
accompanied  at  times  by  an  overturning  of  layers  of  molecules  into 
the  position  which  they  would  occupy  in  a  twin  crystal.  By  this 
process  a  weakness  along  these  planes  is  developed,  and  the  crys- 
talmay^ar^  or  break  with  smooth  surfaces.  This  phenomenon  is 
called  parting  and  is  distinct,  though  not  always  readily  distin- 
guished, from  cleavage,  from  which  it  differs  in  that  it  takes 


FRACTURE. 


225 


place  only  wliere  tJie  molecular  structure  has  been  disturbed  by 
pressure  or  other  agency,  while  cleavage  in  a  given  direction  can 
be  produced  as  readily  in  one  part  of  a  crystal  as  another. 

Magnetite  shows  no  perceptible  cleavage,  but  specimens  from 
certain  localities  show  a  perfect  octahedral  parting  (Fig.  367). 


FIG.  367. 
Octahedral  Parting. — Magnetite. 


FIG.  368. 

Twin  Lamellae  and 
Basal  Parting.— 
Pyroxene. 


Pyroxene  has  a  rather  poor  prismatic  cleavage,  but  some  crystals 
show  twin  lamellae  very  distinctly  and  parting  parallel  to  the 
basal  plane  (Fig.  368). 

Fracture. — If  a  mineral  has  a  poor  cleavage,  and  separates  or 
breaks  almost  as  readily  in  one  direction  as  in  another,  smooth, 
curved  surfaces  often  result  (Fig.  369). 
This  kind  of  fracture  is  called  concTioi- 
dal,  from  its  resemblance  to  the  curved 
surface  of  a  shell.  It  is  especially 
characteristic  of  amorphous  substances, 
such  as  glass,  and  of  minerals  having  a 
poor  cleavage,  such  as  quartz,  while  it 
may  occasionally  be  observed  on  min- 
erals which  cleave  readily,  as  calcite. 

Fracture  is  said  to  be  uneven  when 
rough,  irregular  surfaces  are  obtained  ; 
hackly  when  a  jagged,  irregular  surface  like  that  of  broken 
metal  results  ;  and  splintery  when  the  substance  breaks  in 
splinters  or  needles. 


FIG.  369. 

Conchoidal   Fracture. — Obsidian 
or  Volcanic  Glass. 


226  HARDNESS. 

Tenacity. — A  mineral  is  said  to  be  malleable  when  it  can  be 
beaten  out  into  plates  by  hammering ;  sectile  when  it  can  be  cut 
with  a  knife,  so  that  a  shaving  results  ;  flexible  when  it  bends 
readily,  but  does  not  resume  its  shape  when  the  pressure  is  re- 
lieved ;  elastic  when  it  bends  and  springs  back  to  its  original 
position. 

Hardness. — The  hardness  of  a  mineral,  or  the  resistance  whicli 
it  offers  to  being  scratched,  is  expressed  in  terms  of  a  scale  of 
liardness,  consisting  of  crystallized  varieties  of  the  following  ten 
minerals : 

Scale  of  Hardness. 

1.  Talc.          3.  Calcite.      5.  Apatite.        7.  Quartz.     9.  Corundum. 

2.  Gypsum.  4.  Fluorite.    6.  Orthoclase.  8.  Topaz.     10.  Diamond. 

The  hardness  of  a  mineral  is  determined  by  drawing  a  point,  or 
a  sharp  corner  of  it  across  smooth  surfaces  of  the  different  min- 
erals in  the  scale  of  hardness  until  one  is  found  which  it  will  just 
scratch,  while  it  will  not  scratch  the  next  higher  member  in  the 
scale.  Thus  if  a  mineral  will  scratch  calcite  but  not  fluorite  its 
hardness  will  be  between  3  and  4. 

It  is  generally  a  simple  matter  to  determine  the  hardness  of  a 
mineral,  but 'there  are  some  cases  where  considerable  care  and 
judgment  must  be  exercised.  For  example,  a  soft  mineral  may 
crumble  when  drawn  across  a  harder  one,  especially  when  the  sur- 
face of  the  latter  is  rough,  and  leave  a  mark,  similar  to  that  of 
chalk  on  a  blackboard,  which  readily  rubs  off  and  must  not  be 
mistaken  for  a  scratch.  Again,  it  is  difficult  to  obtain  the  correct, 
hardness  of  minerals  which  crumble  readily  or  crystallize  in  fine 
needles  or  scales,  for  when  drawn  across  the  surfaces  of  the  minerals 
in  the  scale  of  hardness  they  break  down  and  do  not  offer  sufficient 
resistance  to  make  a  distinct  scratch  on  materials  which  may  be 
considerably  softer. 

In  determining  the  hardness  of  minerals  a  knife-blade  will  be 
found  very  useful.  It  will  scratch  apatite  with  some  difficulty, 
but  not  orthoclase,  and  its  hardness,  therefore,  is  a  little  over  5, 


LUSTER.  227 

"With  a  little  experience  an  approximation  to  the  hardness  of  the 
softer  varieties  of  minerals  may  be  obtained  by  noting  the  ease 
with  which  they  are  scratched  with  a  knife.  The  hardness  of 
window-glass  is  about  5£,  and  some  pieces  of  it  will  be  found  very 
useful.  An  ordinary  brass  pin  will  scratch  calcite  but  not  fluorite, 
and  its  hardness  is,  therefore,  a  little  over  3.  The  finger-nail  will 
scratch  talc  easily  and  gypsum  with  some  difficulty. 

Crystals  exhibit  varying  degrees  of  hardness  in  different  direc- 
tions, being  softer  parallel  to  a  cleavage  direction  than  at  right 
angles  to  it.  This  difference,  however,  is  usually  not  sufficiently 
great  to  be  detected  by  the  ordinary  methods  of  testing  hardness. 
Cyanite  furnishes  a  striking  example,  for  in  the  direction  of 
cleavage  (parallel  to  the  longer  axis  of  the  splinters)  it  can  be 
readily  scratched  with  a  knife,  while  at  right  angles  to  the 
cleavage  the  hardness  is  considerably  greater  than  that  of  steel. 

PROPERTIES  DEPENDING  UPON  LIGHT.* 

Luster. — The  luster  of  minerals,  or  their  appearance  due  to 
the  reflection,  absorption,  or  refraction  of  light,  furnishes  an  im- 
portant means  of  identification,  and  is  described  by  the  following 
terms  : 

Metallic. — Having  the  luster  and  appearance  of  a  metal,  like 
lead  or  copper.  Under  this  head  those  minerals  are  included 
which  are  opaque,  that  is,  those  which  are  not  at  all  transparent 
when  their  thin  edges  are  examined  in  a  strong  light.  The  powder 
of  an  opaque  substance  is  black  or  very  dark,  because  the  small 
particles  constituting  it  do  not  transmit  any  light ;  therefore  this 
property  may  be  usefully  employed  in  detecting  metallic  luster. 
Pyrite  and  galena  are  examples  of  minerals  with  metallic  luster. 

Sub-metallic. — Dark-colored  minerals  which  lack  the  true  luster 

*  Though  fully  appreciating  the  importance  of  the  application  of  polarized  light  in 
the  study  of  crystals  and  the  identification  of  minerals,  it  has  seemed  best  not  to  include 
these  methods  in  the  present  work.  For  a  description  of  them  tha  student  is  referred 
to  Idding's  translation  of  Rosenbusch's  Mikroskopische  Physiographic  der  petrographisch 
wichtigen  Mineralien  or  to  Dana's  Text-book  of  Mineralogy. 


228  STREAK. 

of  a  metal  are  called  sub-metallic.  Such  substances  are  generally 
slightly  transparent  in  very  thin  splinters  and  give  dark  powders, 
although  the  colors  are  considerably  lighter  than  those  of  the  com- 
pact minerals.  Chromite,  limonite,  and  some  of  the  dark  varie- 
ties of  sphalerite  are  examples  of  minerals  with  sub-metallic 
luster. 

Non-metallic. — Transparent  minerals  are  here  included.  If  col- 
orless, white,  or  light-colored  they  will  give  white  powders,  and  if 
of  decided  colors  their  powders  will  be  of  lighter  shades  than 
those  of  the  compact  minerals.  For  example,  a  dark-green  epidote 
yields  a  very  pale  green  powder. 

Transparent  minerals  exhibit  the  following  kinds  of  luster: 
Vitreous,  like  the  luster  of  glass.  Adamantine,  like  the  luster  of  a 
diamond.  Minerals  possessing  this  luster  have  a  certain  brilliancy, 
due  to  the  strong  refraction  of  light,  i.  e.,  they  have  a  high  index  of 
refraction.  Adamantine  luster  may  be  observed  on  some  of  the 
hard  minerals  used  as  gems  and  on  cerussite  and  other  transparent 
salts  of  lead.  Resinous,  or  having  the  appearance  of  resin,  as 
shown  by  transparent  varieties  of  sphalerite.  Greasy  or  oily,  as 
if  the  mineral  had  a  thin  coating  of  oil  over  it,  as  shown  by  some 
specimens  of  serpentine  and  massive  quartz.  Pearly,  like  the 
luster  of  mother-of-pearl.  This  is  due  to  the  interference  of  light 
in  minute  cracks  (Newton' s  rings).  It  may  usually  be  observed 
on  crystal  faces  parallel  to  which  there  is  a  perfect  cleavage,  as  on 
the  basal  planes  of  an  apophyllite  crystal.  Silky,  like  a  skein  of 
silk.  This  may  be  observed  on  minerals  which  have  a  fine  fibrous 
structure. 

Streak. — The  streak  of  a  mineral  is  the  color  of  its  powder. 
Provided  the  material  is  not  too  hard,  this  may  be  quickly  de- 
termined by  rubbing  it  on  a  piece  of  white,  unglazed  porcelain, 
and  noting  the  color  of  the  powder,  or  mark,  which  is  left.  Pieces 
of  unglazed  porcelain,  called  streak-plates,  are  made  especially  for 
this  purpose. 

Color.— The  color  of  minerals  is  a  property  which  should  be 
Carefully  considered.  A  mineral  with  metallic  luster  will  always 


COLOR.  229 

show  the  same  tone  of  color  provided  fresJi,  unaltered  ma- 
terial or  a  freslily  broken  surface  is  examined.  Thus,  the  color  of 
chalcocite  is  steel-gray  and  of  bornite  brownish-bronze.  On  ex- 
posure to  the  air  and  light,  however,  the  surfaces  of  minerals  with 
metallic  luster  may  become  dull  or  tarnished  and  present  quite  a 
different  appearance  from  that  of  the  fresh  material.  For  example, 
chalcocite  becomes  black,  and  a  fresh  surface  of  bornite  tarnishes 
to  a  purplish  tint  in  less  than  a  day.  A  mineral  without  metallic 
luster  has  always  a  definite  color  provided  it  contains  a  constituent, 
like  copper,  iron,  or  chromium,  which  has  the  property  of  coloring 
its  compounds.  Thus,  copper  minerals  are  generally  green  or  blue, 
those  containing  iron  and  chromium  generally  green,  though  of 
different  shades,  while  chromates  are  red  or  yellow.  Often,  how- 
ever, the  color  of  a  mineral  with  non-metallic  luster  is  variable,  as 
illustrated  by  fluorite,  which  is  colorless,  yellow,  pink,  green,  and 
violet,  or  by  tourmaline,  which  ranges  from  colorless,  or  white, 
through  varying  shades  of  pink,  green,  blue,  and  brown,  to  black. 
The  causes  for  the  variation  in  color  of  some  minerals  cannot  be 
detected,  since  it  takes  such  minute  quantities  of  certain  materials 
to  impart  color  to  minerals.  In  a  few  cases  the  color  disappears 
upon  the  application  of  heat,  and  is  supposed  to  be  of  the  nature 
of  an  organic  pigment.  In  the  majority  of  cases,  however,  varia- 
tion in  color  is  due  to  the  admixture  of  some  isomorphous  con- 
stituent which  has  the  property  of  absorbing  light.  For  example, 
the  diopside  variety  of  pyroxene,  CaMg(SiO,)2,  is  colorless,  but 
pyroxenes  containing  the  isomorphous  iron  molecule  CaFe(SiOs) 
vary  from  light  to  dark  green,  depending  upon  the  amount  of  iron 
which  they  contain.  As  explained  on  p.  7,  the  variations  in  the 
color  of  sphalerite,  from  colorless,  or  nearly  so,  when  pure  ZnS, 
through  brown  to  black,  depend  upon  the  amount  of  the  iso- 
morphous iron  sulphide  molecule  FeS  which  the  mineral  contains. 
Frequently  a  mineral  is  colored  by  some  foreign  constituent 
with  which  it  is  mechanically  mixed.  Thus  jasper  is  quartz  col- 
ored red  or  brown  by  an  admixture  of  either  hematite  or  li 


230 


FUSIBILITY. 


PROPERTIES  DEPENDING  UPON  HEAT. 

Fusibility. — The  ease  with  which  substances  fuse,  or  their  de- 
gree of  fusibility,  admits  of  approximate  determination,  and  is  of 

great  assistance  in  the  identification 
of  minerals.     In  testing  fusibility, 
splinters  of  nearly  uniform  dimen- 
sions should  be  employed,  and  pieces  about 
1.5  mm.  in  diameter  (Fig.  370)  may  be  as- 
sumed as  the  standard  size.     The  splinter 
should  be  held  in  the  platinum  forceps  so 
that  its  end  projects  beyond  the  metal,  then 
FIG.  370.  heated  as  shown  in  the  figure.     Provided  its 

Method  of  holding  a  frag- 
ment   of   standard   Size  edges  do  not  become  rounded,  a  much  finer 

when  testing  for  the  de-  ..  .        ., 

gree  of  fusibility.  splinter  or  a  fragment  with  a  very  thin  edge 

should  be  tested  before  deciding  that  the  material  is  infusible. 
The  fusibility  of  a  mineral  is  determined  by  comparing  its  fusi- 
bility with  that  of  a  fragment  of  the  standard  size  from  the  fol- 
lowing scale : 

Scale  of  Fusibility.* 

r     A  rather  large  fragment  fuses  easily  in 
-4  a  luminous  lamp  or  gas  flame.     Fusible  in 

la 


1.  Stibnite, 
Sb,S, 


closed  glass  tube  below  a  red  heat. 

C     A  fragment  of   the  standard   size    fuses 
2.  Chalcopyrite,  J  rather  slowly  in  a  luminous  lamp  or  gas 
CuFeSa.          |  flame.     A  small  fragment  fuses  in  a  closed 
^  glass  tube  at  a  full  red  heat. 

C     A  fragment  of  the  standard  size    fuses 
readily  to  a  globule  before  the  blowpipe. 
-<j  In    a  luminous  lamp  or  gas  flame  only  the 
I  very  finest   splinters  or  thinnest  edges  are 
I  rounded. 


3.  Almandine 

Garnet, 
Fe3Al2(SiO4)3. 


*  With  the  exception  of  chalcopyriie  the  scale  here  adopted  is  that  of  Von  Kobell, 
who  mnde  use  of  natrolite  as  No.  2.  Ntilrolite,  however,  seeuis  poorly  chosen,  for  the 
range  between  stibnite  and  natrolite  is  considerable,  while  between  uatrolite  and  garnet 
the  difference  is  slight. 


PYROELECTKICITY.  231 

f     The  edges  of  a  fragment  of  the  standard 
4.  Actinolite,        I  size  are  readily  rounded  before  the  blow- 
Ca(Mg,Fe)3(SiO3)4.     |  pipe.       A    much    finer    splinter    is    easily 
I  fused  to  a  globule. 

i  The  edges  of  a  fragment  of  the  standard 

~    0  ,,     j  size  are  rounded  with  difficulty  before  the 

K  A1S*  O  ^  kl°wPiPe-     I*  ig  only  when  very  fine  splinters 

are  employed  that  the  material  can  be  fused 
^  to  a  globule. 

6.  Bronzite,          (      Only  the  finest  points  and  thinnest  edges 
(Mg,Fe)SiO3.  \  become  rounded  before  the  blowpipe. 

Glowing. — Some  minerals  glow,  or  emit  a  bright  light,  when 
heated  intensely  before  the  blowpipe.  This  is  a  property  of  in- 
fusible substances,  and  the  oxides  of  calcium,  magnesium,  zirco- 
nium, and  thorium  possess  it  in  a  marked  degree.  Fragments  of 
calcite  CaCO3,  brucite  Mg(OH)2,  and  zircon  ZrSiO4,  glow  when  in- 
tensely ignited.  The  Auer  von  Welsbach  light  is  obtained  by  heat- 
ing a  mantle  of  thorium  oxide  with  a  Bunsen-burner  flame. 

Phosphorescence. — Some  minerals  when  gently  heated  become 
luminous  and  emit  light  for  a  longer  or  shorter  period.  This 
property,  known  as  phospJiorescence,  may  be  tested  by  heating 
fragments  of  a  mineral  in  a  closed  tube,  and  best  in  a  dark  room . 
Many  varieties  of  fluorite  phosphoresce  beautifully,  with  purple  or 
green  light.  Some  minerals  phosphoresce  when  they  are  struck  or 
rubbed  ;  others  after  they  have  been  exposed  to  sunlight  or  to  an 
electric  discharge. 

Pyroelectricity. — Some  minerals  when  they  undergo  a  change 
of  temperature  become  electric  and  have  the  property  of  attract- 
ing light  bodies.  This  property,  known  as  pyroelectricity,  is  espe- 
cially characteristic  of  TiemimorpJiic  substances,  i.  e.,  those  which 
show  an  unlike  development  of  crystal  forms  at  opposite  extremi- 
ties of  an  axis  of  symmetry  (p.  164).  Two  kinds  of  electricity  are 
always  developed,  positive  at  one  end  and  negative  at  the  other. 

To  detect  pyroelectricity  a  crystal,  held  in  the  platinum  forceps, 
is  heated  gently  (not  much  above  100°  C.),  and  as  it  cools  it  is  brought 


232  PYEOELECTRICITY. 

near  some  small  bits  of  tissue-paper,  which,  will  be  attracted.  A 
cat' s  hair  which  has  been  rubbed  between  the  fingers  and  become 
positively  electrified  is  excellent  for  detecting  pyroelectricity,  for 
it  will  be  attracted  to  that  end  of  the  crystal  where  negative  elec 
tricity  prevails,  and  repelled  by  the  other.  A  hair  for  this  purpose 
may  be  fastened  to  a  cork  by  means  of  sealing-wax  and  kept  in 
a  vial.  Another  very  beautiful  method  is  tried  with  a  mixture  ol 
about  equal  volumes  of  red  oxide  of  lead  and  flowers  of  sulphur. 
The  mixture  is  kept  in  a  vial,  over  the  mouth  of  which  two  or 
three  thicknesses  of  fine  bolting-cloth  are  tied,  so  that  the  powder 
may  be  sifted  out  slowly.  When  agitated,  the  red  oxide  of  lead 
becomes  positively,  and  the  sulphur  negatively  electrified,  so  that 
when  the  mixture  is  dusted  upon  an  electrified  body  the  red 
oxide  of  lead  will  be  attracted  to  that  part  where  there  is  negative, 
and  the  sulphur  to  where  there  is  positive  electricity.  Experi- 
ments in  pyroelectricity  may  be  made  with  the  lighkcolored 
varieties  of  tourmaline  or  with  crystals  or  fragments  of  calamine. 
Generally  the  experiment  succeeds  best  when  a  rather  small 
fragment  is  employed. 

PROPERTIES  DEPENDING  UPON  WEIGHT. 

Specific  Gravity. — The  specific  gravity  of  a  substance  is  the 
ratio  of  its  weight  to  the  weight  of  an  equal  volume  of  water. 
For  example?  quartz  has  a  specific  gravity  of  2.65,  and  is,  there- 
fore, two  and  sixty-five  hundredths  times  heavier  than  water. 

Specific  gravity  is  a  definite  property  of  all  minerals  which 
show  no  variation  in  chemical  composition,  and,  when  carefully 
determined,  can  be  used  to  great  advantage  as  a  means  of  identifi 
cation.  There  are,  however,  several  conditions  which  must  bo 
carefully  considered. 

1.  It  is  of  the  utmost  importance  that  the  material  should  be 
pure.    If  it  is  not,  there  is  little  or  no  advantage  to  be  gained  by 
taking  its  specific  gravity. 

2.  A  pure,  transparent  fragment  of  a  mineral  will  apparently 
have  a  somewhat  higher  specific  gravity  than  a  piece  which  is  full 


SPECIFIC   GRAVITY.  233 

of  cracks,  as  the  cracks  contain  air  which  tends  to  make  the  min- 
eral lighter.  Air  can  generally  be  expelled  from  cracks  by  boiling 
the  fragment  in  water  for  some  minutes,  when  an  accurate  deter- 
mination may  be  made. 

3.  It  is  difficult  and  often  impracticable  to  obtain  the  correct 
specific  gravity  of  porous,  earthy,  and  fine  fibrous,  or  scaly,  min- 
erals   because   of    the    air  which    they   confine.     Moreover,  the 
chances  of  their  containing  impurities  are  also  great  and  must  be 
taken  into  consideration. 

4.  Minerals  which  show  'a  variation  in  chemical   composition 
may  exhibit  considerable  range  in  specific  gravity.     This  is  espe- 
cially true  when  there  is  an  isomorphous  mixture  of  two  molecules 
with  widely  different  molecular  weights,  as  in  the  case  of  the 
niobate  and  tantalate  of  iron,  explained  on  p.  7.     In  such  cases, 
however,  the  specific  gravity  determinations  may  have  great  value, 
as  furnishing  a  means  of  approximately  determining  the  propor- 
tions of  the  isomorphous  constituents. 

In  the  tables  for  the  determination  of  minerals,  pains  have  been 
taken  to  give,  as  accurately  as  possible,  the  specific  gravity  of  the 
pure  crystallized  varieties  of  each  mineral.  Variations  from  these 
figures  should  be  small,  provided  the  material  that  is  tested  is 
pure  and  its  specific  gravity  is  taken  correctly. 

The  usual  method  for  taking  specific  gravity  is  to  weigh  a  sub- 
stance in  air  and  then  when  immersed  in  water.  The  difference  in 
these  values  is  the  weight  of  a  quantity  of  water  equal  to  the 
volume  of  the  substance,  for  a  body  when  immersed  in  water  is 
buoyed  up  by  a  weight  equal  to  that  of  the  water  displaced.  If 
Wa  is  the  weight  of  a  substance  in  air  and  Ww  its  weight  when 
immersed  in  water,  its  specific  gravity  is  found  by  dividing  Wa 
by  Wa  -  Ww. 

For  very  accurate  determinations  the  weights  should  be  taken 
on  a  chemical  balance.  The  material  is  first  boiled  in  water  for 
some  minutes  to  expel  the  air,  then  allowed  to  cool  in  the  water 
to  the  temperature  of  the  room.  It  is  then  conveniently  placed 
in  a  wire  basket,  suspended  from  the  arm  of  a  chemical  balance 


234 


SPECIFIC    GRAVITY. 


by  a  very  fine  platinum  wire  (Fig.  371),  and  the  weight  in  water 
determined,  from  which  the  weight  of  the  empty  basket  in  water 

should  be  deducted.  The  material  is  then 
weighed,  after  being  thoroughly  dried. 
For  practical  purposes  corrections  for 
temperature  may  be  neglected,  for  they 
will  be  trifling  if  the  weighings  are  made 
at  the  temperature  of  an  ordinary  living- 
room. 

For  quick  results  in  the  identification 
of  minerals,  the  following  simple  methods 
will  be  found  convenient  and  sufficiently 
reliable  for  all  ordinary  purposes. 

The  Spring  or  Jolly  Balance. — With 
this    apparatus    (Fig.   372)    the    relative 
FIG.  371.  weights    of  a  substance  are  determined 

Method  of   hanging  wire  bas-  ,        ,-,          /     ^   7       j>  i 

ket  on  balance  beam  for  by  the  stretch  of  a  spiral 
weighing  substances  in  q-™-^-  Two  -nan<*  arp 
water.  (Wire  basket  at  the  8Prmg- 

side- )  carried  at  the  lower  end  of 

the  spring ;  the  upper  one  c  being  in  the  air 
and  the  lower  one  d  in  water  which  is  in  a 
glass  resting  upon  the  sliding  platform  B.  The 
stretch  of  the  spring  is  read  from  a  scale  which 
is  engraved  upon  a  mirror  fastened  to  the  upright 
A.  A  white  porcelain  bead  at  m  serves  as  a  mark 
for  noting  the  position  of  the  spring  with  refer- 
ence to  the  scale.  It  is  evident  that  in  order  to 
make  these  readings  correctly,  the  eye  must  be 
on  the  same  level  as  the  bead.  This  is  accom- 
plished by  bringing  the  eye  into  a  position  where 
the  top  of  the  bead  and  its  reflection  in  the  mirror 
coincide.  The  pans  being  empty  and  the  lower  .  .  FlG-  372- 

Spring  or  Jolly  Bal- 

one  d  being  suspended  in  the  water  near  the      nnce  for  Specific 

bottom  of  the  glass,  the  position  of  the  bead  m 

is  noted  on   the  scale,  =  x.       A  fragment  of  mineral,  sufficient 


SPECIFIC    GRAVITY. 


235 


to  stretch,  the  spring  somewhat  more  than  one  half  the  length 
of  the  scale,  is  then  placed  in  the  upper  pan  and  the  platform 
lowered  until  the  spring  comes  to  rest,  the  pan  d  occupying 
the  same  relative  position  in  the  water  as  before,  when  the 
position  of  the  bead  is  again  noted,  =  y.  Hence  y  —  x  is  the 
weight  in  air.  The  fragment  is  now  transferred  to  the  lower  pan, 
and  the  platform  raised  until  d  occupies  the  same  position  in  the 
water  as  before,  when  the  position  of  the  bead  is  again  noted,  =  z. 
Hence  y  —  z  is  the  loss  of  weight  in  water  ^  and  the  weight  in  air 
divided  by  the  loss  of  weight  in  water  gives  the  specific  gravity. 

The  Beam  Balance. — This  is  a  simple  piece  of  apparatus  (Fig. 
S73)  which  can  be  easily  constructed.     The  beam  of  wood  is  sup- 

6 


FIG.  373. 
Beam  Balance  for  Specific  Gravity,  ^th  Natural  Size. 

ported  on  a  fine  wire,  or  needle,  at  b  and  must  swing  freely.  The 
long  arm  be  is  divided  into  inches  and  tenths,  or  into  any  decimal 
scale,  commencing  at  the  fulcrum  b  ;  the  short  arm  carries  a  double 
arrangement  of  pans,  so  suspended  that  one  of  them  is  in  the  air 
and  the  other  in  water.  A  piece  of  lead  on  the  short  arm  serves  to 
almost  balance  the  long  arm,  and,  the  pans  being  empty,  the  beam 
is  brought  to  a  horizontal  x>osition,  marked  on  the  upright,  near  c, 
by  means  of  a  rider  d.  A  number  of  counterpoises  are  needed, 
which  do  not  have  to  be  of  any  specific  denomination  as  it  is  their 
position  on  the  beam  and  not  their  actual  weight  which  is  recorded. 
Most  handy  are  bits  of  bent  wire  which  may  be  used  as  shown  at 
A.  The  beam  being  adjusted  by  means  of  the  rider  d^  a  frag- 
ment of  mineral  is  placed  in  the  upper  pan  and  a  counterpoise 
is  chosen,  which,  when  placed  near  the  end  of  the  long  arm,  will 


236  SPECIFIC    GRAVITY. 

bring  it  into  a  horizontal  position.  The  weight  of  the  mineral  in 
air,  TFa,  is  given  by  the  position  of  the  counterpoise  on  the  scale. 
The  mineral  is .  next  transferred  to  the  lower  pan,  and  the  same 
counterpoise  is  brought  nearer  the  fulcrum  b  until  the  beam 
becomes  again  horizontal,  when  its  position  gives  the  weight  of  the 
mineral  in  water,  Ww.  Wa  divided  by  Wa  —  Ww  gives  the  spe- 
cific gravity. 

The  balance  has  been  repeatedly  tested  with  pure  materials,  and 
the  variation  from  determinations  made  on  a  chemical  balance  has 
never  exceeded  two  in  the  second  place  of  decimals.  It  is  reliable, 
quick,  and  sufficiently  accurate  for  all  ordinary  uses. 

The  Heavy  Solution.— By  treating  50  grams  of  mercuric  iodide 
and  40  grams  of  potassium  iodide  in  a  porcelain  dish,  or  casserole, 
with  a  little  water,  and  evaporating  until  a  crystalline  crust  begins 
to  form,  about  30  cubic  centimeters  of  a  yellowish-green  solution  are 
obtained,  which  has  a  specific  gravity  of  about  3.15.  This  may  be 
cleared  by  filtering,  diluted  with  water  to  any  extent,  and  the 
dilute  solution  may  be  brought  to  its  maximum  concentration  by 
evaporation.  It  will  keep  indefinitely  without  decomposition,  pro- 
vided a  few  drops  of  mercury  are  added  to  it.  It  is  very  poison- 
ous. In  determining  the  specific  gravity  of  a  mineral  by  means  of 
the  heavy  solution,  a  fragment  is  placed  in  it,  and  then,  by  adding 
water  cautiously,  the  specific  gravity  of  the  solution  is  lowered 
until  it  becomes  exactly  equal  to  that  .of  the  mineral,  when  the 
fragment  will  remain  suspended  in  any  position,  neither  sinking 
nor  floating.  The  specific  gravity  of  the  solution  may  then  be 
taken  by  some  of  the  methods  described  beyond. 

The  Westplial  Balance. — This  consists  of  a  metal  beam  (Fig.  374) 
with  its  long  arm  from  I  to  7i  divided  into  tenths.  A  glass  sinker  r 
loaded  with  mercury,  is  suspended  from  li  by  means  of  a  fine  plati- 
num wire,  and  the  apparatus  is  so  constructed  that,  with  the  sinker 
in  air,  the  beam-pointer  can  be  brought  to  zero  on  the  scale  s  by 
means  of  the  set-screw  o.  Four  wire  riders  w  are  needed,  of  such 
a  weight  that  one  of  them,  when  hung  at  7^,  will  bring  the  beam- 
pointer  to  zero  when  the  sinker  is  immersed  in  water.  There  are 


SPECIFIC    GRAVITY. 


237 


also  needed  two  lighter  riders,  one  ^V  and  the  other  T^Q-  of  the  unit 
weight.  When  the  sinker  r  is  immersed  in  the  heavy  solution  the 
riders  are  applied,  as  illustrated  in  the  figure,  until  the  beam- 
pointer  stands  opposite  zero.  The  two  ^mY-riders  at  the  end  and 

•r  • 

l  h 


FIG.  374. 
Westphal  Baluuce  for  Taking  the  Specific  Gravity  of  Liquids. 

one  at  6  on  the  beam  indicate  a  specific  gravity  of  over  2.6.  The 
TV  and  yi^  riders,  both  at  5,  furnish  the  second  and  third  figures 
from  the  decimal  point  and  indicate  that  the  specific  gravity 
of  the  solution  is  2.655. 

The  beam-balance  (Fig.  373)  may  also  be  employed.  A  sinker 
similar  to  r  (Fig.  374)  is  suspended  from  a  position  marked  by  a 
notch  near  the  end  of  the  long  arm.  By  putting  shot  in  the  pans 
and  using  the  rider  d  the  beam  is  brought  to  a  horizontal  position 
with  the  sinker  r  in  air.  The  sinker  is  then  immersed  in  the  heavy 
solution  and  a  weight  is  selected,  which,  when  placed  near  the 
end  of  the  beam,  will  bring  the  latter  to  a  horizontal  position. 
The  position  of  this  weight  gives  relatively  the  weight  of  the 
heavy  solution  displaced  by  the  sinker.  After  washing,  the  sinker 
is  immersed  in  water,  and  the  same  weigJit  is  placed  nearer  the 


238  SPECIFIC   GRAVITY. 

fulcrum  until  the  beam  becomes  horizontal.  The  position  of  this 
weight  gives  relatively  the  weight  of  the  water  displaced  by  the 
sinker.  The  larger  weight  divided  by  the  smaller  gives  the  desired 
specific  gravity. 

It  may  often  be  found  convenient,  in  the  identification  of  a  gem, 
to  use  the  heavy  solution  for  comparing  an  unknown  with  a  known 
mineral,  as  follows  :  A  stone  supposed  to  be  beryl 
and  a  known  crystal  of  beryl  are  placed  together 
in  the  heavy  solution,  and  water  is  added  to  deter- 
mine whether  they  sink  and  float  together,  i.  e., 
whether  they  are  identical  in  specific  gravity. 

The  heavy  solution  may  also  be  used  for  obtain- 
ing a  mineral  in  a  state  of  purity  when  mixed  with 
others  of  different  specific  gravity.  The  material  is 
pulverized  and  sifted  to  a  uniform  grain,  then  intro- 
duced into  the  heavy  solution.  The  specific  gravity 
may  then  be  adjusted,  first  so  that  everything 
heavier  than  the  desired  mineral  will  sink,  and  then 
so  that  everything  lighter  will  float.  The  separa- 
tion can  be  most  readily  accomplished  in  the  appa- 
ratus shown  in  Fig.  375. 

Besides  the  potassium  mercuric  iodide  solution, 
which  is  the  cheapest,  and  also  the  easiest  to  pre- 

FIG.  375. 
Separately  Funnel,  pare  and  to  manipulate,  the  following  have  proved 

i  Natural  Size.  „    ,  .11        •    J-T     *  /^TT  T         -^\ 

very  useful :  methylen  iodide,  CH,!,,  with  a  maxi- 
mum specific  gravity  of  3.33,  and  acetylen  tetrabromide,  f  CHBr, — 
CHBra,  with  a  specific  gravity  of  3.01,  both  of  which  may  be  diluted 
with  benzol ;  and  barium  mercuric  iodide,  \  with  a  maximum 
specific  gravity  of  3.55.  The  double  salt,  silver  thallium  nitrate,  § 
melts  at  75°  C.,  giving  a  clear  liquid  with  a  maximum  specific 
gravity  of  over  4.5,  which  may  be  diminished  to  any  desired  extent 
by  adding  hot  water. 

*  R.  Branus,  Jahrbuch  fur  Mineralogie.  1886,  Vol.  II,  p.  72. 
f  W.  Muthman,  Zeitschrift  1'iir  Krystallograpliie.  1898,  Vol.  XXX,  p.  73. 
;  C.  Rohrbach,  Jahrbuch  fur  Mineralogie,  1883,  Vol.  II,  p.  186. 
§  J.  W.  Retgers,  Jahrbuch  fiir  Mineralogie,  1893,  Vol.  I,  p.  90 ;  Author,  Am.  Jour, 
of  Sci.,  1895,  Vol.  L,  p.  446. 


CHAPTER  VI. 

TABLES  FOK  THE  DETERMINATION  OF  MINERAL  SPECIES  BY  MEANS 
OF  SIMPLE  CHEMICAL  EXPERIMENTS  IN  THE  WET  AND  DRY  WAY 
AND  BY  THEIR  PHYSICAL  PROPERTIES. 

INTRODUCTION  TO  THE  TABLES. 

In  the  GENERAL  CLASSIFICATION  of  the  tables  (p.  245)  minerals 
are  divided  into  two  groups  :  I,  WITH  METALLIC  OR  SUB-METALLIC 
LUSTER  ;  II,  WITHOUT  METALLIC  LUSTER,  According  to  the  ex- 
planations on  pp.  227  and  228  this  division  depends  upon  the  fact 
whether  the  minerals  are  opaque  and  give  black  or  dark  streaks, 
or  transparent  and  give  white  or  light-colored  streaks.  Since, 
whether  the  luster  shall  be  considered  metallic  or  non-metallic  is, 
at  times,  wholly  a  matter  of  judgment,  pains  have  been  taken  to 
place  many  minerals  whose  luster  might  be  considered  doubtful 
in  both  sections.  A  further  subdivision  of  each  group  depends 
upon  whether  a  mineral  is  fusible  or  infusible.  The  directions 
given  on  pp.  33  and  230  concerning  fusion  must  here  be  carefully 
considered.  In  making  the  test,  the  degree  of  fusibility  and  per- 
haps some  behavior,  such  as  flame  coloration,  may  be  recorded, 
which  will  be  of  service  in  the  identification  of  the  mineral.  Each 
section  is  then  further  subdivided,  the  divisions  being  based  upon 
some  chemical  constituent  which  may  be  readily  detected,  or  upon 
the  behavior  with  acids. 

In  the  tables  p.  246  et  seq.,  the  two  vertical  columns  at  the  left 
give,  respectively,  the  General  Characters  of  groups  of  minerals 
and  the  Specific  Characters  of  individual  species,  based,  in  most 
cases,  upon  simple  blowpipe  or  chemical  reactions.  In  the  vertical 
columns  headed  Species  the  names  of  the  minerals  are  given  ;  and, 
since  the  tables  are  intended  to  include  all  of  the  minerals  which 
are  recognized  as  distinct  species,  this  number  is  necessarily  large, 

amounting  to  nearly  800  names.     To  facilitate  the  identification  of 

239 


240  INTRODUCTION    TO   THE   TABLES. 

a  single  species  from  this  large  number  the  names  are  printed  in 
three  ways.  Those  in  CAPITALS  indicate  common  minerals,  that  is, 
the  ones  which  are  found  abundantly  and  are  useful  in  the  arts, 
or  as  ores  of  the  metals,  or  are  important  geologically  as  con- 
stituents of  rocks.  Those  in  Fuii-faced  Type  indicate  minerals  which 
are  valuable  or  important,  but  which  do  not  occur  often  enough 
or  in  sufficient  quantity  to  be  considered  as  common.  Names  in 
smaii  type  indicate  rare  minerals.  It  will  probably  be  found  that 
usually  out  of  one  hundred  specimens  to  be  identified  fully 
seventy-five  wiJl  be  the  common  minerals,  printed  in  CAPITALS, 

With  perhaps  twenty  Intermediate  and  five  rare. 

In  the  remaining  columns  the  following  important  properties 
are  recorded :  Chemical  Composition,  pp.  3  to  9  ;  Color,  p.  228 ; 
Streak,  p.  228 ;  Luster,  p.  227 ;  Cleavage  and  Fracture,  pp.  223  to 
225  ;  Hardness,  p.  226  ;  Specific  Gravity,  p.  232  ;  Fusibility,  p.  230  ; 
Crystallization,  pp.  155  to  219. 

METHOD   OF  USING  THE  TABLES. 

The  way  in  which  the  tables  are  used  may  be  illustrated  by  the 
following  examples : 

Celestite. — Referring  to  the  General  Classification  on  p.  245  and 
examining  the  mineral,  it  will  be  seen  that  it  is  without  metallic 
luster,  and  therefore  belongs  in  Group  II.  A  small  fragment  heated 
in  the  forceps  before  the  blowpipe  fuses  rather  readily,  about  3.5 
according  to  the  scale  of  fusibility  (p.  230),  thus  determining  the 
mineral  to  be  in  Section  B.  It  should  be  noted  that  a  red  coloration 
was  imparted  to  the  flame,  indicating,  according  to  the  table  of 
flame  coloration  on  p.  136,  probably  either  strontium  or  lithium. 
The  mineral  is  not  to  be  found  in  Parts  I  and  II  under  B,  because 
when  its  powder  is  fused  with  sodium  carbonate  on  charcoal  it 
does  not  yield  a  metallic  globule,  and  when  fused  alone  it  does  not 
yield  a  black,  magnetic  mass.  It  must,  therefore,  be  in  the 
remaining  Part  III.  It  may  readily  be  proved  to  be  in  Division  1 
under  Part  III,  for  when  a  fused  fragment  is  placed  on  moistened 


INTRODUCTION  TO  THE  TABLES.  241 

turmeric-paper,  it  shows  an  alkaline  reaction.  Further,  a  test-tube 
trial  will  show  that  the  mineral  is  insoluble  in  water,  and  hence  is 
in  section  b  on  page  273.  Referring  to  that  page  the  first  section 
under  General  Characters  comprises  carbonates,  which  dissolve  in 
hydrochloric  acid  with  effervescence.  A  test-tube  trial  of  some  of 
the  powdered  mineral  under  examination  indicates  that  it  is  very 
insoluble  in  acids,  and  therefore  not  a  carbonate.  That  the  mineral 
belongs  to  the  next  section  which  comprises  sulphates  may  readily 
be  proved  by  fusing  a  little  of  it  with  sodium  carbonate  and 
charcoal-powder,  and  thus  obtaining  a  mass  which  gives  a  dark 
stain  when  placed  on  moistened  silver.  The  mineral,  moreover, 
gives  no  water  in  the  closed  tube,  and  is  difficultly  soluble  in 
boiling,  dilute  hydrochloric  acid,  as  shown  by  a  previous  experi- 
ment made  when  testing  for  a  carbonate.  Under  Specific  Charac- 
ters, the  crimson  flame  coloration,  tried  best  on  platinum  wire  as 
directed  on  p.  35,  determines  the  mineral  to  be  celestite,  strontium 
sulphate,  SrSO4.  The  physical  properties  given  in  the  horizontal 
section  should  correspond :  Color,  colorless  or  white;  Luster  mt- 
reous  ;  Cleavage  of  two  kinds,  perfect  in  one  direction,  basal,  and 
less  perfect  in  two  directions,  prismatic,  so  that  a  form  like  Fig. 
273,  p.  201,  may  be  produced ;  Hardness  3  to  3.5,  the  material 
scratches  calcite  and  is  readily  scratched  by  fluorite ;  Specific 
gravity  3.97  ;  Fusibility  3.5,  which  was  determined  at  the  outset ; 
Crystallization,  orthorhombic,  crystals  being  perhaps  like  Figs.  278 
or  279,  p.  202.  If  the  specific  gravity  had  been  taken  at  the  begin- 
ning it  would  have  served  to  distinguish  celestite  from  all  the 
other  minerals  in  Division  1,  b,  pp.  273  and  274,  for  there  are  none 
which  come  at  all  close  to  3.97. 

CJiromite. — The  color  of  this  mineral  is  black,  and  the  powder, 
or  streak,  is  dark  brown  ;  hence  the  luster  may  be  considered  as 
sub-metallic,  and  the  mineral  classified  in  Group  I,  p.  245.  At 
the  beginning,  the  hardness  may  be  determined  as  between 
5  and  6,  and  the  specific  gravity  as  4.6.  When  heated  before  the 
blowpipe  there  is  no  indication  of  fusion  ;  the  mineral  is  therefore 
in  Section  B.  Division  1,  under  B,  includes  minerals  containing 


242  PRECAUTIONS   IN   THE   USE   OF   THE   TABLES. 

iron,  which  become  magnetic  after  heating,  but  if  a  trial  is  made 
it  will  be  found  that  the  mineral  does  not  become  magnetic.  In 
Division  2  the  minerals  containing  manganese  are  included.  A 
test  made  with  borax  in  the  oxidizing  name,  as  directed,  gives  a 
bead  which  is  yellow  when  hot  and  yellowish  green  when  cold. 
This  does  not  indicate  manganese,  but  is  a  decided  reaction  for 
chromium,  as  may  be  seen  by  referring  to  the  table  of  reactions 
obtained  with  borax  on  p.  148.  Since  the  mineral  fails  to  give  re- 
actions for  iron  and  manganese,  it  must  belong  in  Division  3— Not 
belonging  to  the  foregoing  divisions,  p.  256.  Referring  to  this  page 
in  the  column  General  Characters,  the  mineral  cannot  be  in  the 
first  section  because  of  its  hardness.  It  is,  however,  in  the  second 
section,  since  the  borax-bead  test,  previously  made,  has  indicated 
the  presence  of  chromium.  This  reaction,  as  well  as  the  determi- 
nations of  hardness  and  specific  gravity,  agree  with  chromite, 
FeCr,O4  =  FeO.Cr2Oa.  A  test  for  iron  may  be  made  with  the 
magnet  after  fusion  with  sodium  carbonate  on  charcoal,  as  directed 
under  Specific  Characters.  Had  the  chromite  been  considered  as 
being  without  metallic  luster,  Group  II,  p.  245,  it  would  have  been 
found  under  C,  Division  5,  b,  p.  298. 

Precautions  in  the  Use  of  the  Tables.— The  system  adopted 
in  the  construction  of  the  tables  is  that  of  eliminating  one  group 
of  minerals  after  another  until  a  species  is  found,  whose  properties, 
as  given  in  the  table,  correspond  to  the  mineral  that  is  being 
tested.  The  process  of  elimination  and  identification  is  based 
largely  upon  a  series  of  chemical  tests  which,  in  almost  all  cases, 
give  an  insight  into  the  character  of  the  material.  There  is  dan- 
ger, however,  that  one  may  become  so  absorbed  in  following  the 
tables  mechanically,  with  the  sole  idea  of  determining  the  name  of 
the  species,  as  to  wholly  lose  sight  of  the  importance  of  making  a 
careful  study  of  the  chemical  reactions  and  physical  properties  of 
the  minerals.  It  should  be  distinctly  understood  that  little  or 
nothing  is  to  be  gained  by  simply  determining  the  name  of  a 
mineral.  The  chief  aim  should  be  to  obtain  a  thorough  faiowl- 
edge  of  the  chemical  composition,  physical  properties,  and  gen- 


PRECAUTIONS  IN  THE  USE  OF  THE  TABLES.  243 

eral  appearances  and  associations  of  a  mineral,  not  only  that 
its  uses  and  relations  may  be  understood,  but  also  that  it  may  be 
easily  recognized  and  identified  when  again  encountered. 

The  general  plan  and  arrangement  of  the  tables  must  be  ad- 
hered to  rather  closely,  for  if  they  are  applied  in  the  reverse  direc- 
tion, that  is,  backwards,  they  may  not  lead  to  the  desired  result. 
For  example,  if  a  mineral  has  metallic  luster,  is  fusible,  and  gives 
a  reaction  for  sulphur,  it  does  not  necessarily  belong  to  Division  5 
under  I,  A  (p.  245),  for  most  of  the  minerals  containing  arsenic 
(Division  1)  and  antimony  (Division  4)  also  contain  sulphur.  It 
is,  therefore,  not  correctly  determined  as  belonging  to  Division  5 
until  proof  has  been  obtained,  not  alone  of  the  presence  of  sul- 
phur, but  also  of  the  absence  of  arsenic  and  antimony,  as  well  as 
of  the  rare  elements  selenicum  and  tellurium  (Divisions  2  and  3). 

The  tables  are  adapted  to  the  determination  of  pure  minerals. 
If  it  is  thought  that  a  mineral  is  not  pure  the  nature  of  the  im- 
purity must  be  taken  into  careful  consideration.  Thus,  for  ex- 
ample, many  minerals  are  associated  with  calcite,  CaCO3.  If  some 
of  this  is  included  in  material  that  is  being  tested  it  will  cause  a 
slight  effervescence  with  acids  and  an  alkaline  reaction  when  the 
ignited  material  is  applied  to  moistened  turmeric-paper,  although 
both  reactions  are  probably  entirely  foreign  to  the  mineral  which 
it  is  desired  to  determine.  The  best  and  almost  the  only  rule  to 
guide  one  in  such  cases  is  one' s  judgment.  It  would  be  impossible 
to  devise  blowpipe  methods  to  meet  the  contingencies  arising 
from  the  various  mixtures  of  minerals.  The  one  thing  of  the 
very  utmost  importance  is  the  assurance  of  the  purity  and  homo- 
geneous character  of  a  mineral.  Since,  in  most  cases,  only  a  very 
little  material  is  required  for  the  necessary  tests,  by  careful  selec- 
tion enough  can  generally  be  secured  in  a  pure  condition. 

RECORD    OF    MINERAL    TESTS. 

A  careful  record  should  be  kept  of  all  tests  as  they  are  made. 
it  may  be  found  convenient  to  record  them,  together  with  the 


244  RECORD    OF    MINERAL   TESTS. 

physical  properties,  upon  blanks  similar  to  the  accompanying 
sample.  It  is  not  intended  that  every  test  for  which  a  space  has 
been  allotted  should  be  made,  but  a  convenient  place  has  been  fur- 
nished where  the  prominent  blowpipe  reactions  may  be  recorded, 
provided  tests  in  the  closed  or  open  tubes  or  with  the  fluxes,  etc., 
have  been  made. 


Structure 

System  of  crystallization 

Cleavage  or  fracture 

Luster Color 

Streak Hardness Sp.  Gr. 

Fusibility Flame  color 

Effect  of  acids  aud  reactions  with  the  solution 


Closed  tube 

Open  tube 

Alone  on  charcoal 

With  fluxes  on  charcoal 

With  fluxes  on  platinum  wire. 
Miscellaneous 


NAME COMPOSITION. 

Per  cent  of  chief  constituents 

Mode  and  place  of  occurrence 

Associations 

Uses 

Number Date .. 


*  Fifty  of  these  blanks,  bound  in  book  form,  may  be  obtained  from  the  publishers. 
50  cents,  net. 


(Page  245.) 

/ 

ANALYTICAL  TABLE 


SHOWING    THE 


GENERAL    CLASSIFICATION 


OP 


MINERALS. 


ABBREVIATIONS  USED  IN  THE  TEXT  OF  THE  TABLES. 


Amorph...  Amorphous. 
Approx...  Approximately. 

B.  B Before  the  blowpipe. 

Botryoid..  Botryoidal. 

C Cleavage. 

Capill Capillary. 

01 Class. 

Colum Columnar. 

Cryst Crystalline;  in  crystals. 

Direc Direction. 

F Fracture. 

Fig Figure. 

Fol Foliated. 

Fus Fusibility. 

Gran Granular. 

H Hardness. 

HC1 Hydrochloric  acid. 

HNO3 Nitric  acid. 

H,SO4 Sulphuric  acid. 

Hemiinor .  Heminiorphic. 

Hexag Hexagonal. 

Hex.  Rh..  Hexagonal  Rhombohedral, 
Incrust....  Incrusting;  incrustation. 

Isom Isometric. 

Isom.  Pyr.  Isometric  Pyritohedral. 


Isom.  Tet. 
iso.  w. . . . 
Marnin.... 
Mammill.. 

Mass 

Moiiocl . . . 
Na9CO,  . . 

Oct 

O.F 

Orthorh  . . 

per 

Pinac  

Prism 

Pseudom. . 
Pyram  — 

Radiat 

R.F 

Sp.  Gr. . . . 

Sph 

Tabul 

Tar 

Tetrag.... 
Tet.  Sph.. 

U 

Vol  . . 


Isometric  Tetrahedral. 

Isomorphous  with. 

Mammillary. 

Mammillary. 

Massive. 

Mouoclinic. 

Sodium  carbonate. 

Octahedral. 

Oxidizing  flame. 

Orthorhombic. 

Perfect;  referring  to  cleavage. 

Piuacoidal;  in  one  direction. 

Prismatic. 

Pse  u  do  in  o  rphous. 

Pyramidal. 

Radiated. 

Reducing  flame. 

Specific  Gravity. 

Spheuoidal. 

Tabular. 

Tarnish. 

Tetragonal. 

Tetragonal  Sphenoidal. 

Usually. 

Volatile. 


N.B. — The  chemical  symbols  of  the  elements,  together  with  the  valences  which  they 
ordinarily  exhibit  in  mineral  combinations  and  their  atomic  weights,  will  be  found  in 
Chapter  III  "  Reactions  of  the  Elements,"  pp.  41  to  134. 


245 


GENERAL    CI 


Success  in  using  the  folloiving  fables  depends  ivliolly  upon  locating  a  mi 
initial  reactions,  as  given  in  this  GENERAL   C 


In  testing  the  solubility  of  minerals  the  importance  of  using  ve 
\.    MINERALS  WITH  METALLIC  OR  SUB-METALLIC  LUSTER. 

NOTE  —Minerals  Laving  metallic  luster  are  opaque;  hence  the  color  of  their  powder,  or  the: 
streak  is  dark  though  not  necessarily  black  (p.  227).     The  minerals  with  sub-metallic  luster  whic 
are  included  in  this  section  all  give  dark-colored  streaks.    Many  dark-colored  minerals  who* 
is  doubtful  have  been  placed  here,  and  also  in  Section  II. 


A.— FUSIBLE  FROM  1-5,  OR  EASILY  VOLATILE. 


PAC; 


1.  Roasted  in  the  open  tube,  or  B.  B.  on  charcoal,  give  a  volatile  sublimate  of  Arsenious 

Oxide(p.  48).     Compare  Antimony,  Section  4 •••••     2- 

2.  Roasted  in  the  open  tube,  or  B.  B.  on  charcoal,  give  the  characteristic  radish-like  < 

Selenium.     Impart  an  azure-blue  color  to  the  reducing  flame  (p.  107) 2 

3.  Treated  in  a  dry  test-tube  with  3  cc.  of  concentrated   H3S04  and  gently  heated,  the  acid 

assumes  a  reddish-violet  color  characteristic  for  Tellurium  (p.  124) 2- 

4.  Roasted  in  the  open  tube,  or  B.  B.  on  charcoal,  give  a  dense  white  sublimate  of  Oxide  of 

Antimony  (p.  44).     The  sublimate  is  less  volatile  than  that  of  arsenic 

5.  Roasted  in  the  open  tube,  or  B.  B.  on  charcoal,  give  the  odor  of  Sulphurous  Anhydride 

(p.  118),  but  do  not  give  the  reactions  of  the  preceding  divisions 

6.  Not  belonging  to  the  foregoing  divisions ~ 

B.-INFUSIBLE,  OR  FUSIBLE  ABOVE  5,  AND  NON-VOLATILE. 

1    Become  magnetic  after  heating  B.  B.  in  the  reducing  flame,  Iron  (p.  84) 2 

2.  A  minute  quantity  of  material  imparts  to  the  borax  bead  in  O.  F.  a  reddish-violet  cc  lor, 

Manganese  (p.  93) 2 

3.  Not  belonging  to  the  foregoing  divisions 

II.    MINERALS  WITHOUT  METALLIC  LUSTER. 

NOTE  —Minerals  without  metallic  luster  are  transparent,  although  they  may  have  such  a  da 
color  that  ihey  transmit  light  only  through  very  thin  edges.  The  color  of  their  powder,  or  their  strec 
is  generally  white  or  light-colored,  never  black  (p.  228). 

A.-EASILY  VOLATILE,  OR  COMBUSTIBLE. 

1.  Rapidly  disappear  when  heated  B.  B.  on  charcoal.     Only  a  few  minerals  behave  thus 


B.-FUSIBLE  FROM  1-5,  AND  NON  VOLATILE,  OR  ONLY  SLOWLY  OR 

PARTIALLY  VOLATILE. 

Partl.-Give  a  METALLIC  GLOBULE  on  charcoal. 

1.  Fused  B   B   on  charcoal  with  sodium  carbonate  give  a  globule  of  Silver  (p.  113).  .......... 

2.  Fused  B.  B.  on  charcoal  with  sodium  carbonate  and  charcoal  dust  give  a  globule 

and  a  coating  of  Lead  Oxide  (p.  87). •  •  •  •  •  •  •  •  •  •  • ; •  •  •  "•' 

3.  Fused  B.  B.  on  charcoal  with  sodium  carbonate  and  charcoal  dust  give  a  glol 

and  a  coating  of  Bismuth  Oxide  (p.  54) 


OSSIFICATION.  345 

ral  with  certainty  in  the  group  to  which  it  belongs;  hence  it  is  evident  that  the 
3IFICATION,  should  be  tried  with  the  utmost  care. 

fine  powder?  ground  in  an,  agate  mortar,  can  not  be  overestimated. 

PAGE 

4.  Fused  B.  B.  on  cLarcoal  with  sodium  carbonate  and  charcoal  dust  give  a  globule  of  Anti- 

mony and  a  coating  of  Antimony  Oxide  (p.  44) 263 

5.  Fused  B.  B.  on  charcoal  with  a  mixture  of  equal  parts  of  sodium  carbonate  and  borax  give  a 

globule  of  Copper  (p.  73).     The  powdered  mineral  on  charcoal,  after  moistening  with 
hydrochloric  acid,  imparts  an  azure-blue  color  to  the  blowpipe  flame 263 

Part  II. — Become  Magnetic  after  Heating  before  the  blowpipe  in  the 

reducing  flame,  Iron. 

1.  Soluble  in  hydrochloric  or  nitric  acid  without  perceptible  residue,  and  without  yielding  gela- 

tinous silica  upon  evaporation.    Mostly  Sulphates,  Arsenates  and  Phosphates.    266 

2.  Soluble  in  hydrochloric  or  nitric  acid  and  yield  gelatinous  silica  on  evaporation,  or  are  decom- 

posed with  the  separation  of  silica,  Silicates 269 

3.  Insoluble  in  hydrochloric  acid 270 

Part  III. — Do  NOT  give  a  metallic  globule,  and  do  NOT  become  magnetic. 

1.  Give  an  alkaline  reaction  on  moistened  turmeric-paper  after  intense  ignition  before  t7ie  blowpipe, 

held  either  in  the  forceps  or,  if  very  easily  fusible,  in   a  loop  on  platinum  wire.     Salts 
of  the  Alkali  and  Alkali-earth  Metals. 

a)  Easily  and  completely  soluble  in  water 271 

b)  Insoluble  in  water,  or  difficultly  or  only  partly  soluble. . .   273 

2.  Soluble  in  hydrochloric  acid,  but  do  not  yield  a  jelly  or  a  residue  of  silica  on  evaporation. 

Mostly  Arsenates,  Phosphates  and  Borates 275 

3.  Soluble  in  hydrochloric  acid  and  yield  gelatinous  silica  on  evaporation.     Soluble  Silicates. 

a)  In  the  closed  tube  give  water 278 

b)  In  the  closed  tube  give  little  or  no  water 279 

4.  Decomposed  by  hydrochloric  acid  with  the  separation  of  silica,  but  without  going  wholly  into 

solution  and  without  giving  a  jelly  on  evaporation.     Decomposable  Silicates. 

a)  In  the  closed  tube  gi  ve  water 281 

b)  In  the  closed  tube  give  little  or  no  water 283 

5.  Insoluble  in  hydrochloric  acid.     Mostly  Insoluble  Silicates. 283 

C.— INFUSIBLE,  OR   FUSIBLE  ABOVE  5. 

1.  Give  an  alkaline  reaction  on  moistened  turmeric-paper  after  intense  ignition  before  the  blow- 

pipe.   Salts  of  the  Alkali-earth  Metals 289 

2.  Soluble  in  hydrochloric  acid,  but  do  not  yield  a  jelly  or  a  residue  of  silica  on  evaporation. 

Mostly  Carbonates,  Sulphates,  Oxides,  Hydroxides  and  Phosphates.....  290 

3.  Soluble  in  hydrochloric  acid  and  yield  gelatinous  silica  on  evaporation.     Soluble  Silicates.  294. 

4.  Decomposed  by  hydrochloric  acid  with  the  separation  of  silica,  but  without  going  wholly  into 

solution  and  without  giving  a  jelly  on  evaporation.     Decomposable  Silicates 295 

5.  Insoluble  in  hydrochloric  acid. 

a)  Hardness  less  than  that  of  glass  or  steel      Can  be  scratched  by  a  knife 29fr 

b)  Hardness  equal  to  or  greater  than  that  of  glass.    Can  not  be  scratched  by  a  knife.  298- 


(Page  246.) 

1.  MINERALS   WITH   METALLIC  OE  SUB-METALLIC  LUSTEE. 

A.— Fusible  from  1-5,  or  Easily  Volatile. 
DIVISION  1. — Arsenic  Compounds,  in  part. 


246  I.   MINERALS   WITH   METALLI' 

A.— Fusible  from  1— 

DIVISION  1. — Arsenic  Compounds. — When  heated  before  the  blowpipe  on  charcoal,  a  whit 
of  arsenic  is  often  obtained,  p.  48.     Of  other  reactions  for  arsenic,  roasting  in  the  open  tube  is  espec 

N.  B. — The  minerals  in  this  division  are  chiefly 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

B.  B.  volatile  without  fusion. 

In  the  closed  tube  gives  a  sublimate  of  arsenic. 

Arsenic. 

B.  B.  on  charcoal  fuses,  and 
gives  a  white  coating  of  oxide 
of  antimony. 

In  the  closed  tube  gives  a  sublimate  of  arsenic, 
leaving  a  fused  globule  of  antimony. 

Allemontite. 

Contain  lead     With  NaaCOs  on 

Distinguished    by  crystallization    and    specific 
gravity. 
Sartorite  decrepitates  strongly. 

Sartorite. 

charcoal  give  globules  of  lend 
and  a  coating  of  lead  oxide. 
Oxidized  by  concentrated 
HNOs  with  the  separation  of 
lead  sulphate. 

Dufrenoysite. 

Guitermauite. 

Jordanite. 

Contains  silver.  —  With  Na2CO3 
on  charcoal  in  O.  F.,  gives  a 
globule  of  silver. 

The  dilute  HNO9  solution  assumes  a  blue  color 
when  treated  with  ammonia  in  excess  (copper). 

Pearceite.     See 

polybasite,  p.  260. 

Contain  copper  and  sulphur.— 
Roasted  on  charcoal,  then 
moistened  wi  h  HOI  and  again 
ignited,  dve  a  blue  or  green 
flame.  The  HNO3  solution  is 
rendered  blue  by  addition  of 
ammonia  in  excess.  When 
roasted  in  an  open  tube  the 
odor  of  sulphur  dioxide  is 
evolved. 

In    the   KNO3    solution,    ammonia    produces   a 
rather  abundant  precipitate  of  ferric  hydroxide. 

Epigenite. 

Contain    little    or    no  iron.     Distinguished  by 
physical  properties. 
Euargite  is  easily  cleavable,  the  others  are  not. 

Enargite. 

Teniantite.     See 
tetraliedrite,    p. 
250. 

Binnite. 

Lautite. 

Contain  copper,  reactions  as 
above,  but  no  sulphur. 

Distinguished  by  physical  properties.      All  ex- 
hibit a  brownish  tarnish  on  exposed  surfaces. 

Domeykite. 

Algodonite. 

Whitneyite*. 

Contain    cobalt        Give    to    the 

With  potassium  iodide   and  sulphur,  on  char- 
coal, give  the  reaction  for  bismuth,  p.  55,  §  2. 
Distinguished  by  differences  in  crystallization. 

Alloelasite. 

Bismutosmaltite. 

borax  bead  a  sapphire-  blue 
color.  The  concentrated  HNO3 
solution  generally  shows  a  del- 
•cate  rose  color,  thus  distin- 
guishing the  cobalt  from  the 
nickel  minerals  on  the  next 
page. 

Give  a  sublimate  of  arsenic  in  the  closed  tube, 
find  contain  little  or  no  sulphur. 
EJp  Compare    Chloanthite,  p.  247,  which   often 
contains  sufficient  cobalt  to  give  a  blue  color  to 
the  borax  bead. 

Smaltite. 

Safflorite. 

Skutterudite. 

Give  reactions  for  both  sulphur  and  arsenic  in 
the  open  lube.     In  the  closed  tube  a  sublimate 
of  arsenic  is  not  formed  except  upon  intense 
ignition. 

Cobaltite. 

Slaucodot. 

DIVISION  1- — Arsenic  Compounds. — Concluded  on  next  page. 


OR   SUB-METALLIC   LUSTER.  246 

or  Easily  Volatile. 

oating  of  arseuious  oxide  deposits  at  a  considerable  distance  from  the  assay,  and  a  garlic-like  odor 
Y  recommended,  and,  in  some  cases,  heating  in  the  closed  tube  gives  decisive  results. 

arsenides  and  sulpliarsenites  of  Hie  metals,  p.  47. 


Composition. 

Color. 

Streak. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

Hex.  Kb.' 
U.  gran. 

>. 

Tin-white. 
Tar.  dark  gray. 

Gray. 

C.  Basal,  per. 

3.5 

5.7 

Vol. 

;  with  Sb. 

Tin-white. 
Tar.  gray. 

Gray.  _ 

C.  Basal,  per. 

3.5           0.20 

1 

Hex.  Bh. 
U.  gran. 

)S.  As2S3. 

Lead-gray. 

Dark  brown  to 
black. 

C.  Basal, 
F.  Conchoidal. 

3              5.40 

1 

Orthorh. 

'bS.As2S3. 

Blackish  -gray. 

Dark-  brown  to 
black. 

C.  Basal,  per. 

3 

5.56 

1 

Monocl. 

•bS.As2S3? 

Bluish-gray. 

Black. 

F.  Uneven. 

3 

5.9               1 

Massive. 

'bS.As.,S3. 

Blackish-gray. 

Black. 

C.  Fiuacoidal. 
F.  Uneven. 

3 

6.40             1 

Monocl. 
Monocl. 

ig,  €11)28.  As2Ss. 

iso.  w.  As. 

Black. 

Black. 

F.  Conchoidal. 

3 

6.15             1 

'u2S.3FeS.As2Sa? 

Steel-gray. 

Black. 

F.  Uneven. 

3.5                              2? 

Orthorh. 

!u9S.AsaSB.f 

Grayish-black 

Gray  -black. 

C.  Prism.,  per. 
F.  Uneven. 

O 

4.44 

1 

Orthorh. 
U.  cryst. 

!u2S.As2S3. 

2,Zn,  and  Fe  iso.  w. 
?ua;  Sb  iso.  w.  As. 

Blackish-gray, 

Black  to  deep 
cherry-red. 

F.  Uneven. 

3-4 

4.6 

1.5. 

1  so  m.  Tet, 
Cryst.  & 
Mass. 

!uaS.2As2S3. 

Iron-black. 

Black. 

F.  Couchoidal. 

2.5-3 

4.47 

1.5? 

Isometric. 

lAsS. 

Iron-black. 

Black. 

C.  not  distinct. 

3 

4.9 

1.5? 

Prismatic. 

i,As. 

Steel-gray. 

Gray. 

F.  Uneven. 

3-3.5 

7.5 

2 

Massive. 
Massive. 

eAs. 

Steel-gray. 

Gray. 

F.  Uneven. 

4 

7.6 

2 

i9As. 

Silver-white. 

Silver-white. 

Malleable. 
F.  Hackly. 

3.5 

8.5 

2 

Massive. 

(As,Bi)S. 

.  iso.  w.  Co. 

Steel-gray. 

Black. 

C.  Prism.,  per. 
F.  Uneven. 

4.5 

6.6 

2? 

Ortliorh. 
U.  Colum. 

<As,Bi)3. 

Tin-white. 

Black. 

6 

6.92 

2? 

Isometric. 

.As2. 

and  Ni  iso.  w.  Co. 

Tin  -white. 

Black. 

C.  Octahedral. 
F.  Uneven. 

5.5-6 

6.3-6.5 

2.5 

Isom.Pyr. 

>Asa. 

iso.  \v.  Co. 

Tin-white. 
Tar.  dark-gray 

Black. 

C.  Piuacoidal. 
F.  Uneven. 

4.5-5 

6.9-7.3 

2.5 

Orthorh. 

•As,. 

Tin-white  to 
lead  -gray. 

Black. 

F.  Uneven. 

6 

6.75 

2.5 

Isom.Pyr. 

»AsS. 
iso.  w.  Co. 

Tin-white,  with 

reddish  tone. 

Black. 

3.  Cubic. 
F.  Uneven. 

5.5 

6-6.2 

2-3 

Isom.Pyr 
Orthorh. 

o,Fe)AsS. 

Grayish-white. 

Black. 

C.  Basal. 
F.  Uneven. 

5 

5.95 

2-3 

(Page  247.) 
1.  MINERALS  WITH  METALLIC  OR  SUB-METALLIC   LUSTER. 

A.— Fusible  from  1-5,  or  Easily  Volatile. 
DIVISION  1. —Arsenic  Compounds,  concluded. 
DIVISION  2. — Selenium  Compounds,  in  part. 


247 


I.   MINERALS   WITH    METAL! 

A.— Fusible  fron 
DIVISION  1. — Arsci: 


General  Characters. 

Specific  Characters. 

Name  of  Species 

Contain  nickel.—  Impart  to  the 
borax  bead  a  reddish-brown 
color.  Give  apple  -  green- 
colored  solutions  when  dis- 
solved in  HNO3,  which  be- 
come blue  when  diluted  and 
treated  with  ammonia  in  ex- 
cess. (This  reaction  for  nickel 
must  not  be  confounded  with 
the  more  intense  blue  which  is 
produced  when  solutions  con- 
taining copper  are  similarly 
treated.) 

Give  a  sublimate  of  arsenic  in  the  closed  tube, 
and  contain  little  or  no  sulphur. 

Chloanihite. 

Rammelsbergite. 

On  intense  ignition  in  the  closed  tube  gives  a 
slight  sublimate  of  arsenic. 
[Sf0  Compare  Breithauptite,  p.  250. 

Niccolite. 
(Copper  Nickel.) 

Gives  reactions  for  both  sulphur  and  arsenic  in 
the  open  tube,  but  contains  no  antimony.  In 
the  closed  tube  a  sublimate  of  arsenic  is  not 
formed  except  upon  intense  ignition. 

Gersclorfite. 

Give  reactions  for  sulphur,  antimony,  and  arsenic 
in  the  open  tube. 

Corynite. 

Wolfachite. 

Contain  iron.  —  B.  B.  fuse  to 
strongly  magnetic  globules. 
The  dilute  HNO3  solution, 
when  treated  with  ammonia  in 
excess,  yields  a  reddish-brown 
precipitate  of  basic  ferric  a?'- 
senate. 

Gives  reactions  for  both  arsenic  and  sulphur  in 
the  open  tube.  Gives  an  abundant  sublimate 
of  arsenic  in  the  closed  tube. 

ARSENOPYRITE. 

(Mispickel.) 

Contains  no,  or  only  a  trace  of,  sulphur.  Massive 
varieties  can  be  identified  with  certainty  only 
by  means  of  a  quantitative  chemical  analysis. 

Lollingite. 

Leucopyrite. 

Contains  platinum. — Foasted  in  the  open  tube,  at    first  very  gently,  a  platinum 

sponge  is  left,  which  is  insoluble  in  any  single  acid.    Fuses  readily  to  a  globule  Sperrylite. 
when  heated  rapidly  on  charcoal.     Test  for  platinum  as  directed  on  p.  103. 


DIVISION  2. — Selenium  Compounds. — When  heated  before  the  blowpipe  on  charcoal,  t 
nzure-blue,  p.  107. 

N.B.— The  minerals  in  this  division  are  mostly  the  seleir< 


Contains  tellurium.  —  B.  B. 
wholly  volatile. 

In  the  open  tube  u  sublimate  of  TeOa  is  formed, 
which  fuses  to  colorless  drops. 

Selen-tellunum. 

Contain  mercury.  —  Heated  in  the 
closed  tube  with  Na2CO3,  give 
metallic  mercury  (p.  94).  Heat- 
ed alone  in  the  closed  tube, 
give  a  metallic-gray  sublimate 
of  mercuric  seleuide.  B.  B. 
wholly  volatile. 

Fused  with  Na3CO3  on  charcoal,  gives  globules 
of  lead  and  a  coating  of  lead  oxide. 

Lehrbachite. 

Gives  sulphur  dioxide  when  heated  in  the  open 
tube. 

Onofrite. 

Contains  no,  or  only  a  trace  of,  sulphur. 

Tiemannite. 

Contain  copper.  —  Fuse  B.  B.  to 
globules  which,  after  moisten- 
ing with  HC1,  color  the  flame 
azure-blue.  The  HNO3  solu- 
tion is  rendered  deep-blue  by 
addition  of  ammonia  in  excess. 

When  heated  alone,  B.  B.  colors  tue  name  green 
(thallium). 

Crookesite. 

The  HNO3  solution  gives  with  HC1  a  white  pre- 
cipitate of  silver  chloride. 

Eucairite. 

The  HNO3  solution  gives  with  H2SO4  a  precipi- 
tate of  lead  sulphate. 

Zorgite. 

Contain  only  selenium  and  copper. 

Berzelianite. 

Umangite. 

DIVISION  2.— Selenium  Compounds.— Concluded  on  next  page. 


OR   SUB-METALLIC   LUSTER. 

—5,  or  Easily  Volatile. 
Compounds. — Concluded. 


24? 


Composition. 

Color. 

Streak. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

JiAs2. 

'e  and  Co  iso.  w.  Ni. 

Tin-white. 

Black. 

C.  Octahedral. 
F.  Uneven. 

5.5-6 

6.4-6.8 

2 

Isom.Pyr. 

T..                             ;Tin-white,with 
reddish  tinge. 

Black. 

C.  Prismatic. 
F.  Uneven. 

5.5-6 

** 

6.9-7.2 

2 

Orthork. 

IAs. 

b  and  S  iso.  w.  As. 

Pale  copper- 
red. 

Brownish- 
black. 

F.  Uneven. 

5-5.5 

7.5 

2 

Hexag 
U.  mass. 

Isom.Pyr. 

HAsS. 

e  and  Co  iso.  w.  Ni. 

Tin-white. 

Black. 

C.  Cubic. 
F.  Uneven. 

5.5 

5.8-6.2 

2 

l(As,Sb)S. 

Tin-white. 

Black. 

F.  Uneven. 

4.5-5 

6.0 

2 

Isometric. 

l(As,Sb)S. 

Steel-gray. 

Black. 

C.  Prismatic. 
F.  Uneven. 

4.5 

6.6 

2 

Orthorh. 
U.  coluin. 

'eAsS. 

occasionally  Co  iso.  w. 
Fe. 

Silver-white. 

Black. 

C.  Prismatic. 
F.  Uneven. 

5.5-6 

6-6.2 

2 

Orthorh. 
U.  cryst. 
Page  203. 

'eAsa. 

Silver-while. 

Black. 

C.  Basal. 
F.  Uneven. 

5-5.5 

7.2-7.3 

2 

Orthorh. 

'e3As4. 

Silver-white. 

Black. 

F.  Uneven. 

5-5.5 

6.9-7.1 

Massive. 

'tAs3. 

Tin-white. 

Black. 

F.  Conchoidal 

6-7 

10.60 

2 

Isom.Pyr. 

haracteristic  radish-like  odor  of  selenium  is  obtained,  and  the  reducing  flame  is  tinged  a  beautiful 
of  the  metals.     None  of  them  are  of  common  occurrence. 


'e  with  Se. 

Blackish-gray.  Black. 

C.  Prismatic, 
perfect. 

2-2.5 

1 

Hexag. 

Massive. 

>b,Hg)Se. 

Lead  -  gray    to 
iron-black. 

Black. 

7.85 

1 

Massive. 
Massive. 

[g(S,Se). 

Blackish-gray. 

Black. 

F.  Conchoidal. 

2.5 

8.0 

Vol. 

feSe. 

Blackish-gray. 

Black. 

F.  Conchoidal. 

2.5 

8.2 

Vol. 

Isom.Tet. 
U.  mass. 

Massive. 

;u,Tl,Ag)2Se. 

Lead-gray. 

Black. 

F.  Uneven. 

2.5-3 

6.9 

1 

uAg  Se. 

Lead-gray. 

Shining. 

2.5 

7.5 

2 

Isometric. 
U.  mass. 

*b,Cua)Se. 

Lead-gray. 

Black. 

2.5 

7-7.5 

1 

Massive. 
U.  gran. 

u2Se. 

K  iso.  \v.  Ctl. 

Silver-white. 

Shining. 

F.  Uneven. 

2  ? 

6.7 

1.5 

Massive. 

u3Sea. 

Dark     cherry- 
red. 

Black. 

3 

5.62 

1.5 

Massive. 

(Page  248.) 

I.  MINERALS   WITH   METALLIC  OR  SUB-METALLIO  LUSTER. 
A. — Fusible  from  1-5,  or  Easily  Volatile. 

DIVISION  2.— Selenium  Compounds,  concluded. 
DIVISION  3.— Tellurium  Compounds. 


248 


I.    MINERALS   WITH   METALLI 

A.— Fusible  from  1- 

Di  VISION  2. — Selenium 


General  Characters. 

Specific  Characters. 

Name  of  Species 

Contain  silver.  —  Give  a  globule 
of  silver  when   heated  B.  B. 
on  charcoal  with  borax. 
t^°  Compare  Eucairite,  p.  247. 

The  HNOs  solution  gives  with  H2SO4  a  precipi- 
tate of  lead  sulphate. 

Naumannite. 

Give  the  odor  of  sulphur  dioxide  when  roasted 
in  the  open  tube. 

Aguilarite. 

Contains  lead,  but  does  not  give  the  reactions  of  the  foregoing  groups.  —  Fused 
with  Na2CO3  on  charcoal,  gives  globules  of  lead,  and  a  coating  of  lead  oxide. 

Clausthalite. 

Contains  bismuth. — Heated  on  charcoal  with  the  potassium  iodide  and  sulphur 
mixture,  gives  a  red  sublimate  (p.  55,  §  2). 


Guanajuatite. 


DIVISION  3. —Tellurium  Compounds.— If  a  little  of  the  powdered  mineral  is  treated  ii 
beautiful  reddish-violet  color,  p.  124. 

N.B.— The  minerals  in  this  division  are  mostly  the 


B.  B.  wholly  volatile. 

On  charcoal  fuses,  tinges  the  reducing  flame 
green,  and  gives  a  white  coating  near  the  assay. 

Tellurium. 

Globules  of  mercury  are  obtained  by  heating 
with  NaQCO3  in  the  closed  tube  (p.  94). 

Coloradoite. 

With    NaaCO3   on 
charcoal  in  R.  F. 
yield       metallic 
globules. 

Bismutli. 

With  potassium  iodide  and  sulphur  on  charcoal 
a  red  sublimate  is  obtained  (p.  55.  §  2).  Griin- 
lingite  and  some  varieties  of  Tetradymite  react 
for  sulphur  in  the  open  tube.  Tapalpite  reacts 
for  both  silver  and  sulphur. 

Tetradymite. 

Griinlingite. 

Tapalpite. 

Lead. 

The  HNOa  solution  with  H3SO4  gives  a  precipi- 
tate of  lead  sulphate. 

Altai  te. 

Nagyagite. 

Silver. 
2£^~    Com- 
pare Tapal- 
pite  above. 

Alone  on  charcoal  in  O.  F.  gives  a  globule  of 
silver  which  may  contain  some  gold. 

Hessite. 

Gold,  usually 
with  Silver. 

Slightly  sectile  to  brittle. 

Petzite.    ' 

Distinctly  cleavable.     Very  brittle. 

Sylvanite. 

Krennerite. 

Uneven  to  conchoidal  fracture.     Very  brittle. 

Calaverite. 

Contains  nickel.  —  The  roasted  mineral  imparts    a    reddish-  brown  color  to  the 
borax  bead. 

Melonite. 

OR   SJB-METALLIC   LUSTER, 
or  Easily  Volatile, 
impounds.— Concluded. 


2-18 


Dmposition. 

Color. 

Streak. 

Cleavage  and 
Fracture. 

Hard. 

ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalliza- 
tion. 

Lga,Pb)Se. 

Iron-black. 

Black. 

C.   Cubic. 

2.5 

8.0 

2 

Isometric. 
U.  mass. 

gaSe.AgaS. 

Iron-black. 

Black. 

F.  Hackly. 

2.5 

7.6 

1 

Isometric. 

bSe. 

Lead-gray. 

Black. 

C.  Cubic. 

2.5-3 

7.8-8.5 

2 

Isometric. 
U.  gran. 

iaSe3. 

Bluish-gray. 

Black. 

C.  Pinacoidal, 

perfect. 

2.5-3.5 

6.3-6.6 

1.5 

Orthorh. 
U.  col  urn. 

test-tube  with  about  3  cc.  of  concentrated  sulphuric  acid,  and  gently  heated,  the  acid  assumes  a 
lurides  of  the  metals.     They  are  of  rare  occurrence. 


'e. 

Tin-white. 

Gray. 

C.  Prismatic, 
perfect. 

2-2.5 

6.1-6.3 

1 

Hex.  Rh. 

[gTe. 

Iron-black. 

Black. 

F.  Uneven. 

3 

8.63 

1 

Massive. 

iaTe3,  more  often 
2Bi2Te2.Bi2S3. 

Tin-white. 

Gray. 

C.  Basal,  jttr. 

1.5-2 

7.6-7.3 

1.5 

Hex.  Rh. 

i«S,Te. 

Pale  steel-gray 

Gray. 

C.  Basal,  per. 

1.5-2 

7.32 

1 

Hexag. 

Aga(S,Te). 
Bia(S,Te)s. 

Pale  steel-gray 

Gray. 

Sectile. 

7.8 

1 

Massive. 

'bTe. 

Tin-white. 

Gray. 

C.  Cubic. 

3 

8.16 

1.5 

Isometric. 
U.  mass. 

.uaPl)14Sb3Te7Si7? 

Blackish  -gray. 

Black. 

C.   Pinacoidal, 
perfect. 

1-1.5 

6.9-7.2 

1.5 

Orthorh. 
U.  f<>l. 

g*Te. 

u  iso.  w.  Ag. 

Steel  -gray. 

Gray. 

F.  Uneven. 

2.5-3 

8.3-8.8 

1 

Isometric. 

kg,Au)2Te. 

Iron-gray. 

Gray. 

F.  Uneven. 

2.5-3 

8.7-9.0 

1.5 

Massive. 

.uAgTe4. 

Silver-white. 

Gray. 

C.  Pinacoidal, 
perfect. 

1.5-2 

8-8.2 

Monocl. 

.uTea,    with    Ag 
iso.  w.  Au. 

Silver-  white. 

Gray. 

C.  Basal,  per. 

2.5 

8.35 

1 

Orthorn. 

.uTe2,    with     Ag 
iso.  w.  Au. 

Silver-white. 

Gray. 

F.  Uneven. 

2.5 

9.35 

1 

Monocl. 

ftaTe2. 

Reddish-white. 

Darn-gray. 

C.  Basal,  per. 

Hexag. 

(Page  249.) 

I.  MINERALS  WITH  METALLIC  OE  SUB-METALLIC  LUSTER 

A.— Fusible  from  1-5,  or  Easily  Volatile. 
DIVISION  4.— Antimony  Compounds,  in  part. 


249 


L  MINERALS   WITH   METALL1 


A.— Fusible  from  1- 

DIVISION  4. — Antimony  Compounds. — Wbeu  heated  before  the  blowpipe  on  charcoal  t 
with  the  open  tube  may  also  be  recommended. 

N.  B. — Most  of  the  minerals  in  this  division  are  the  sulphantimoni-es  < 


General  Characters. 


Easily  and    completely  volatil 
when  heated  B.  B.  on  charcoal. 
Do  not  give  reactions  for  lead 


Specific  Characters. 


ID  the  open  tube  yields  a  white,  slowly  volatile, 
crystalline  sublimate  of  Sb3O3  (p.  45). 


In  the  open  tube  yields  S02  and  for  the  most 

sublimate  o 


Name  of  Species. 


Antimony. 


Reacts  for  mercury  when  heated  in  the  closet 
tube  with  NaaCO8. 


Livingstonite. 


Contains  copper. — When  decomposed  by  HNO3 
and  treated  with  ammonia  in  excess,  the  solu- 
tion assumes  a  deep  blue  color. 


Bournonite. 


Contains    bismuth.  —  Fused    on    charcoal    with 
potassium  iodide  aud  sulphur  gives  a  -red  sub-  Kobeliite. 
limate. 


Contain  lead.  —  After  carefully 
rousting  on  charcoal  (p.  89)  the 
residue,  when  scraped  up  with 
Na3CO3  and  fused  in  R.  F., 
gives  globules  of  metallic  lead. 

The  iodine  tests  for  lead  (p.  89 
are  very  decisive. 

When  roasted  alone  on  churcoa 
are  nearly  or  completely  vol 
atile. 

Oxidized  by  concentrated  nitric 
acid,  with  the  separation  of 
metantimonic  acid  (p.  46,  §  6) 
lead  sulphate,  and  usually  of 
sulphur. 

Compare   Galena  (p.    251), 
which,  when  roasted  alone  on 
charcoal,    sometimes    gives 
coating    resembling     that    of 
antimony  (p.  88). 


Contain  silver.—  The  HNO3  solution,  filtered  if 
necessary,  gives  with  HC1  a  precipitate  of  silvei 
chloride  which  is  insoluble  in  hot  water  (differ- 
ence from  lead  chloride,  p.  89,  §4). 

A  globule  of  silver  is  obtained  by  continued 
heating  on  charcoal  in  O.  F. 


Andorite. 


Bronguiardite. 


Diaphorite. 


Freieslebenite, 


Contain  tin. — When  heated  in  O.  F.  on  charcoal 
leave  an  infusible  mass  of  oxide,  which,  when 
mixed  with  Na3COa  and  charcoal  powder 
aud  fused  in  R.  F.,  gives  a  malleable  metallic 
globule. 


Cylindrite. 
(Kj-lindrite.) 


Franckeite. 


Zinkenite. 


Plagionite. 


Warren  ite. 


Contain  neither  copper,  bismuth,  tin,  nor  silver. — 
The  minerals  are  distinguished  by  differences 
in  crystallization  and  physical  properties. 


Jamesonite. 
(Feather  Ore.) 


Semseyite. 


Boulancrerito. 


Meneghiniie. 


Geocrinite. 


Kilbrickenite. 
Spiboulangerite. 


DIVISION  4.— Antimony  Compounds.— Continued  on  next  page. 


OR   SUB-METALLIC   LUSTER. 


249 


or  Easily  Volatile. 

ense  white  coating  of  oxide  of  antimony  deposits  near  the  assay  (p.  44).     The  test  for  antimony 

e,  metals.     The  sulphur  may  be  detected  by  roasting  in  the  open  tube. 


Composition. 

Color. 

Streak. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Graviij'. 

Fusi- 
bility. 

Crystalli- 
zation. 

Tin-  white. 

Gray. 

C.  Basal,  per. 

3-3.5 

6.6-C.7 

1 

Hex.  Kh. 
U.  gran. 

)2S3           \/ 

Lead-gray. 

Gray-black. 

C.  Pinacoidai, 
perfect. 
F.  Uneven. 

2 

4.55 

1 

Orthorh. 
P;ige  202. 

jS.2SbaS,. 

Lead-gray. 

Reddish. 

2 

4.81 

1 

? 
Prismatic. 

'bS.Cu2S.Sb2S3. 

Steel-gray. 

Black. 

F.  Uneven. 

2.5-3 

5.  SO 

1 

Orthorh. 
U.  cryst. 

bS.(Bi,Sb)2S3. 

Blackish-  gray. 

Black. 

2.5-3 

6.30 

1 

Massive. 
Prismatic. 

bS.AgaS.3SbaS3. 

Dark     steel- 
g'-ay. 

Black. 

F.  Couchoidal. 

,3-3.5 

5.33 

1 

Orthorh. 

)S.Ag2S.Sb2S3. 

Grayish-black. 

Black. 

F.  Uneven. 

3-3.5 

5.95 

1 

Massive. 

5b,Ag2)S.2Sb2S3. 

Steel-gray. 

Black. 

F.  Uneven. 

2.5-3 

5.9-6.0 

1 

Orthorh. 

3b,Ag2)S.2Sb2S3. 

Steel-gray. 

Black. 

F.  Uneven. 

2-2.5 

6.2-6.4 

•4 

Mouocl. 

bS.6SuS2.Sb2S3. 

Blackish-gray. 

Black. 

F.  Uneven. 

2.5-3 

5.42 

1.5 

Rolls. 

bS  2SnSa.Sba83. 

Blackish-gray. 

Black. 

C.  Piuacoidal. 

2.5-3 

5.55 

1 

Tabular. 

)S.Sb2S3. 

Steel-gray. 

Black. 

F.  Uneven. 

3-3.5 

5.35 

1 

Orthorh. 

'bS.4Sb2S3. 

Blackish  -gray. 

Black. 

F.  Uneven. 

2.5 

5.40 

1 

Monocl. 

'bS.2SbaS8. 

Blackish-gray. 

Black. 

1 

Capillary. 

'bS.Sb2S3. 

Blackish-gray. 

Black. 

C.  Basal,  per. 
F.  Uneven. 

2-3 

5.5-6.0 

1 

Orthorh. 
U.  capill. 

bS.3Sb2S3. 

Gray. 

Black. 

C.  Pyramidal. 

5.95 

1 

Monocl. 
U.  tabul. 

bS.Sb2S3. 

Bluish      lead- 
gray. 

Black. 

F.  Smooth. 

2.5-3 

5.75-6.0 

1 

Gran.  & 
Compact. 

bS.Sb2S3. 

Blackish-gray. 

Black. 

C.  Pinac.,  per. 

2.5 

6.35 

1 

Orthorh. 
U.  prism. 

bS.SbaSs. 

Lead-gray. 

Black. 

C.  Prismatic. 
F.  Uneven. 

2.5 

6.40 

1 

Orthorh. 
U.  mass. 

bS.Sb2S3? 

Lead  -gray. 

Black. 

6.40 

1 

Massive. 

bS.Sb2SB. 

Blackish-gray. 

Black. 

6.31 

1 

Orthorh.? 
Prismatic. 

(Page  250.) 

1.  MINERALS   WITH   METALLIC  OR  SUB-METALLIC  LUSTER. 

A.— Fusible  from  1-5,  or  Easily  Volatile. 
DIVISION  4 — Antimony  Compounds,  concluded. 


250 


I.   MINERALS   WITH   MBTALL1 

A.— Fusible  from 
DIVISION  4.— Antimo 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

Contain  silver,  but  do  not  give 
the     foregoing    reactions    for 
lead.  —  After  decomposing  with 
HNO3  and  filtering,  the  solu- 
tion reacts  for  silver  with  HC1. 
When  only  the  volatile  elements, 
antimony    and    sulphur,    are 
present  with  silver,  a  globule 
of  the  pure  metal  may  be  ob- 
tained by  fusion  and  continued 
heating  on   charconl  in  O.  F. 
The  coating  of  oxide  of  anti- 
mony in  this  case   assumes  a 
reddish  to  deep  lilrnc  tint  (p. 
114).     Often,  after  the  volatile 
constituents    have    to  a   large 
,    extent  been  driven  away,  the 
addition  of  a  liitle  Na2C03,  or 
borax,  assists  in  the  formation 
of  the  silver  globule. 

Contain  copper.  —  When  decomposed  by  HNO3 
and  treated  with  ammonia  in  excess,  a  deep 
blue  solution  is  obtained. 
S^T"  Compare  Polybasite,  below. 

Stylotypite. 

Freibergite. 

(Silver  Tetrahedrite. 

Sulphantimonites    of    silver,   containing  no,   or 
only  traces  of,  copper.     Give  the  odor  of  sul- 
phur dioxide  when  roasted  in  the  open  tube. 
The  crystals  of  Steplmnite  are  usually  stout,  six- 
sided  prisms.     Those  of  Polybasite  six-sided 
plates,  with  triangular  markings  on  the  basal 
planes. 

Miargyrite. 

Pyrargyrite. 
(Dark  Ruby-silver. 

Stephanite. 

Polybasite.     See 
pearceite,  p.  246. 

Polyargyrite. 

Reacts  only  for  antimony  and  silver. 

Dyscrasite. 

Contain  copper,  but  neither  lead 
nor  silver.  —  The  dilute  HNO3 
solution,  filtered  if  necessary, 
gives  a  deep  blue  color  with 
ammonia  in  excess. 

Gives  globules  of  mercury  when  heated  in  a 
closed  tube  with  dry  Na2CO3  (p.  94,  §  1). 

Schwatzite. 
(Mercurial  Tetra- 
hfdrite.) 

Distinguished  by  differences  in  crystallization 
and  physical  properties. 

Chaleostibite. 
(Wolfsbergite.) 

Falkenhaynite. 

TETRAHEDRITE. 

(Gray  Copper.) 

Famatinite. 

Contains  iron,  but  does  not  give 
the  reactions  of  the  foregoing 
divisions. 

Fuses  to  a  strongly  magnetic  globule. 

Berthierite. 

Contains  nickel.  —  The   roasted 
mineral   gives  with  borax   in 
O.  F.  a  brownish  bead. 

React  for  sulphur  in  the  open  tube.  With 
potassium  iodide  and  sulphur  give  the  test  for 
bismuth  (p.  55,  §  2). 

Kallilite. 

Hauclieeornite. 

Reacts  for  sulphur,  but  contains  no  bismuth. 

Ullinannite. 

Contains  little  or  no  sulphur.  Some  varieties 
react  for  arsenic. 

Breithauptite. 

OR   SUB-METALLIC   LUSTER. 
5,  or  Easily  Volatile. 
Compounds. — Concluded. 


250 


Composition. 

Color. 

Streak. 

Cleavage  and 
Fracture. 

Hard- 

11  ess. 

Specific 
Gravity. 

Fusi- 
bility. 

CrystaMi- 

zation. 

}u2,Aga,Fe)S. 
SbaS3. 

Iron-black. 

Black. 

F.  Uneven. 

3 

4.8 

1-1.5 

Orthorh. 

)u,Ag)aS.SbaSs. 
and  Zn  iso.  w.  Cua. 

Gray. 

Black. 

F.  Uneven. 

3-4 

4.7-4.9 

1.5 

Isom.  Tet. 
Page  175. 

52S.Sb2S3. 

Iron-black. 

Dark  -  red     to 
black. 

F.  Uneven. 

3-2.5 

5.1-5.3 

1 

Monocl. 

g,S.SbaS,. 

Deep  -  red     to 
black. 

Indian-red. 

C.  Rhomboh. 
F.  Conchoidal. 

2.5 

5.85 

1 

Hex.  Rh. 
Hemimor. 

C1.13,  p.2!9. 

.gjS.SbaSs. 

Iron-black. 

Black. 

F.  Uneven. 

2-2.5 

6.2-6.3 

1 

Orthorh. 

A.ff,Cu)aS.SbaSi. 
iso.  w.  Sb. 

Iron-black. 

Black. 

F.  Uneven. 

2-3 

6-6.2* 

1 

Monocl. 

AgaS.SbaS8. 

Iron-black. 

Black. 

C.  Cubic. 

2.5 

6.95 

1 

Isometric. 

*3Sb. 

Silver-gray. 
Tar.  black. 

Gray. 

C.  Basal. 

3.5-4 

9.75 

1.5 

Orthorh. 

}ua,Hg)S.SbaS8. 

and  Zn  iso.  w.  Cu2. 

Dark  -gray. 

Black. 

F.  Uneven. 

3-4 

4.8-5.1 

1.5 

Isom.  Tet. 
P.-ige  175. 

i.S.SbaS8. 

Blackish-gray. 

Black. 

C.  Basal,  per. 

3-4 

4.95-5.0 

1 

Orthorh. 

!u2S.SbaS3. 

Grayish  -black 

Black. 

4.83 

1-1.5 

Massive. 

3iiaS.SbaS8. 

,Zn,Pb  and  Aga  iso. 
v.  Cn2:  As  iso.  w.  Sb. 

Gray. 

Black. 

F.  Uneven. 

3-4 

4.7-5.0 

1.5 

Isom.  Tet. 
Page  175. 

;u2S.Sb2S5. 

Gray,     with 
reddish  tone. 

Black. 

F.  Uneven. 

3.5 

4.57 

1-1.5 

Orthorh. 

;S.Sb2S3. 

Steel-gray. 

Black. 

C.  Longitudi- 
nal. 

2-3 

4-4.3 

1.5-2 

Prismatic. 
Fibrous. 

i(Sb,Bi)S. 

Light     bluish- 
gray. 

Black. 

7.01 

Massive. 

i(Bi,Sb,S). 

Bronze-yellow 

Black. 

5 

6.4 

Tetrag. 
U.  mass. 

iSbS. 

Silver-gray. 

Black. 

C.  Cubic,  per. 

5-5.5 

6.5-6.7 

1.5 

Isometric. 
Cl  5.  pi  29 

iSb. 
5  iso.  w.  Sb. 

Copper-red, 
violet  tone. 

F.  Uneven. 

5-5.5 

7.54 

1.5-2 

Hexag. 

(Page  251.) 

I.  MINERALS  WITH   METALLIC   OE  SUB-METALLIC  LUSTER. 

A.— Fusible  from  1-5,  or  Easily  Volatile. 
DIVISION  5.— Sulphides,  in  part. 


25" 


I.   MINERALS   WITH   METALIJ 
A.— Fusible  from  1- 


DIVISION  5.—  Sulphides.  —  "When  roasted  in  the  open  tube  sulphur  dioaide  (sulphurous  anli 
a  piece  of  moistened  litmus-paper  placed  in  the  upper  end  of  the  tube.     The  reactions  of  the 


N.B.  —  The  minerals  in  this  division  are  mostly  sulphides  of  the  metals.     Sulphides  containing 
will  be  met  with  later  on  among  the  minerals  without  metallic  luster. 


General  Characters. 

Specific  Characters. 

Name  of  Species 

Contain  only  silver  and  sulphur. 

Sectile,  can  be  cut  with  a  knife  like  lead. 

Argentite. 

coal    in    O.    F    a    globule  of 
pure  silver  is  obtained. 

Acauthite. 

Contain   lismuth.  —  Mixed   with 
potassium  iodide  and  sulphur, 
uud  fused  on  charcoal  in  O.  F. 
a  red  sublimate  is  obtained  (p. 
55,  §2). 
When  lead  is  present,  the  yellow 
coating  of  lead  iodide  may  ob- 
scure the  foregoing  reaction  for 
bismuth.      In  order  to   make 
decisive  tests  for  the  two  ele- 
ments it   is   recommended    to 
proceed  as  follows:   Treat  ai 
ivory-spoonful  of  the  powder- 

Reacts only  for  sulphur  and  bismuih. 

Bismuthinite. 

(Bismuth  Glance 

Contain  lead  and  silver.  —  Decompose  with  HNOs 
dilute  with  water,  and  filter.  In  the  filtrate 
HC1  will  produce  a  precipitate  of  silver  chlo 
ride  which  is  insoluble  in  boiling  water. 

Schirmerite. 

Schapbachite. 

Contain  lead,  and  not  more  than  traces  of  silver. 
—  Aikenite  is  characterized  by  containing  cop- 
per, otherwise  it  may  not  be  possible  to  identify 
the  rare  minerals  in  this  group  without  a  quan- 
titative chemical  analysis. 

Chiviatite. 

Rezbanyite. 

Galenobismutite. 

Cosalite. 

ed  mineral  in  a  test-tube  with 
3  cc.   of  HNO3  and  1  cc.  of 
concentrated  H2SO4  ,  and  boil 
until  the  nitric  acid  is  expelled. 
After    cooling,   add   5  cc.   of 
water,  boil  for  about  a  minute 
in  order  to  dissolve  the  bismuth 
sulphate,  and  filter  off  the  in- 
soluble   lead    sulphate.      This 
may  be  tested  by  fusing  with 
NaaCOs  on  charcoal.     In    the 
filtrate  precipitate  the  bismuth 
as  hydroxide   with   ammonia, 
filler,  and  test  some  of  it  by 
fusing  on   charcoal   with    the 
potassium  iodide  and  sulphur 
mixture.     If  copper  is  present 
the  amuioniucal    filtrate   from 

the  bismuth  will  be  blue. 

\ 

Aikinite. 

Lillianite. 

Beegerite. 

Contain  copper.  —  When  decomposed  by  nitric 
acid,  the  dilute  solution  is  rendered  blue  by 
the  addition  of  ammonia  in  excess. 

Cuprob'smntite. 

implectite. 

Klaprotholite. 

Wittichenite. 

Contains  silver,  but  neither  lead  nor  copper.  — 
Gives  a  globule  of  silver  when  fused  with 
borax  and  Na2CO3  on  charcoal. 

Matildite. 

Contains  lend,   but   no  bismuth. 
—  With    Na2CO3   on   charcoal 
gives   globules  of  lead  and  a 
yellow  coating  of  lead  oxide. 

Oxidized  by  concentrated   nitric  acid  with  the 
separation  of  lead  sulphate  and  usually,  also, 
of  some  sulphur. 

GALENA. 

E3f  Compare  Cylindrite  and  Franckeite  (p.  250),  which  do  not  give  very  distinct 
antimony  reactions. 

DIVISION  5. — Sulphides.— Continued  on  next  page. 


OR   SUB-METALLIC   LUSTER, 
or  Easily  Volatile. 


251 


ide)  is  formed,  which  may  be  recognized  by  its  odor,  and  by  the  acid  reaction  which  it  imparts  to 
g  divisions  should  not  be  obtained. 

enic,  antimony,  selenium,  and  tellurium  will  be  found  in  the  foregoing  divisions.  A  few  sulphides 


Composition. 

Color. 

Streak. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

g,s. 

Blackish-gray. 

Blackish-  gray. 

F.  Conchoidal. 

2-2.5 

7.3 

1.5 

Isometric. 

gaS. 

Iron-black. 

Black. 

F.  Uneven. 

2-2.5 

7.2-7.3 

1.5 

Orthorh. 

JiaS3. 

Lead  -gray. 

Gray. 

C.  Pinacoidal, 

perfect 

2 

6.4-0.5 

1 

Oilhorh 
Prismatic. 

(Aga,Pb)S.2BiaS3. 

Lead-gray. 

Grayish-black. 

F.  Uneven. 

6.75 

1-1.5? 

Massive. 

'bS.AgaS.BiaS8. 

Lead-gray. 

Grayish-black. 

C.  Basal. 

3.5 

6.43 

1-1.5? 

Orthorh.? 

PbS.SBiaS,. 

Lead  -gray. 

Grayish-black. 

C.  Distinct. 

6.92 

1-1.5? 

Foliated. 

PbS.5BiaS3. 

Light     lead- 
gray. 

Grayish-black. 

F.  Uneven. 

2.5-3 

6.1-6.4 

1-1.5? 

Massive. 

bS.BiaSs. 

Lead-gray. 

Grayish-black. 

3-4 

6.8-7.1 

1-1.5? 

Columnar 

PbS.BiaS3. 

Pa,C"a  &  Fe  iso.w.Pb. 

Lead-gray. 

Grayish-black. 

F.  Uneven. 

2.5-3 

6.4-6.7 

1-1.5 

Orthorh. 
U.  mass. 

Pb,Cua)S.BiaS8. 

Blackish  lead- 
gray.. 

Grayish-black. 

F.  Uneven. 

2-2.5 

6.7 

1-1.5 

Orthorh. 
Acicular. 

PbS.BiaSs. 
eaiso.  w.  Pb;  Sbiso. 
w.  Bi. 

Steel-gray. 

Grayish-black. 

6.1 

1-1.5? 

Massive. 

PbS.Bi2S3. 

jra  i*o.  w.  Pb. 

Gray. 

Grayish-black. 

C.  Cubic? 

7.27 

1-1.5? 

Isometric? 

Du,S.4Bi8Ss. 

g  iso.  AV.  On. 

Bluish-black. 

Black. 

6.3-6.8 

1 

Slender 
prisms. 

UaS.BiaSs. 

Grayish-white. 

Black. 

C.  Piuacoidal, 

perfect. 

2 

6.3-6.5 

1 

Orthorh. 

DllaS.SBiaSs. 

Steel-gray. 

Black. 

F.  Uneven. 

2.5 

4.6? 

1 

Orthorh. 

JaaS.BiaSs. 

Grayish-white. 

Black. 

F.  Conchoidal. 

3.5 

6.70 

1 

Orthorh. 

g,8.BiaSs. 

Gray. 

Gray. 

2-3? 

6.92 

1-1.5? 

Slender 
prisms. 

bS. 

Lead-grajr. 

Grayish-black. 

C.  Cubic,  per 

2.5 

7.6 

2 

Isometric, 
U.  cryst. 
or  gran. 

(Page  252.) 

I.  MINERALS  WITH  METALLIC  OR  SUB-METALLIC   LUSTER. 

A.— Fusible  from  1-5,  or  Easily  Volatile. 
DIVISION  5.— Sulphides,  continued. 


252 


I.   MINERALS   WITH   METALLI 
A.-l 


L.— Fusible  from 
DIVISION  5.— S« 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

aut  do  not  give  the  reactions  of  the  foregoing 
ie  roasted  minerals,  moistened  with  HCI  and 
n  charcoal,  impart  an  azure-blue  color  to  the 
ilute  HNOs  solution  is  rendered  blue  by  ad- 
onia  in  excess.  This  latter  test  must  not  be 
vith  the  somewhat  similar  one  for  nickel, 
present  the  blue  color  is  not  conspicuous  un- 
lydroxide  precipitate  has  been  filtered  off. 

Contain    iron, 
and   fuse  to 
magnetic 
globules.  — 
From        the 
HNO3   solu- 
tion   ammo- 
nia   precipi- 
tates   ferric 
hydroxide. 

Color  brass-yellow.  —  When  massive,  Cubanite 
can  scarcely  be  told  from  Chalcopyrite  except 
by  a  quantitative  chemical  analysis. 

CHALCOPYRITE. 

(C'opper  Pyrites.) 

Cubanite. 

Color  purplish,  and  somewhat  variegated  011  ex- 
posed surfaces,  but  brownish-bronze  on  a  fresh 
fracture. 
R5P"  Compare  Chalcocile  below,  which  at  times 
contains  sufficient  iron  as  an  impurity  to  make 
it  magnetic  after  heating. 

BORNITE. 

(VariegatedOopper, 
Peacock  Ore.) 

Fused  alone  on  charcoal  the  coal  near  the  assay 
becomes  covered  with  a  white  coating  of  oxide 
of  tin.  Only  slightly  magnetic  after  heatingB.B. 

Stanniie. 
(Tin  Pyrites.) 

Contain  cobalt. 

The  roasted  minerals  impart  a  blue  color  to  the 
fluxes. 

Carrollite. 

Syclmodymite. 

Contain     neither 
iron  nor  cobalt. 
Do  not  fuse  to 
magnetic  glob- 
ules. 
JEST0  Comp.  Stan- 
nite          above, 
which  does  not 
become     mag- 
netic except  af- 
ter long  heating 
B.  B. 

From  the  HNO3  solution  *ilver  chloride  is  precip- 
itated by  the  addition  of  HCI. 

Stromeyerite. 

-5  °  -  a  ^  *  ~ 
-SllggJjJ 

z:>  s  issg~- 

S'C^tH-s  ul>^ 
0 

The  finely  powdered  mineral,  after  careful 
roasting  on  charcoal  (p.  40),  gives  in  R.  F.  a 
globule  of  copper.  Gives  no  sulphur  in  the 
closed  tube. 

CHALCOCITE. 

(Copper  Glance.) 

Reacts  like  the  foregoing,  except  that  much  sul- 
phur is  obtained  by  heating  in  the  closed  tube. 

Covellite. 

1   -ill 

Contains  silver 
and  iron. 

Fused  with  borax  on  charcoal  in  O.  F.  gives  a 
globule  of  silver. 

Sternbergite. 

3.  B.  fuse  to  magnetic  globules,  due  to  the  presence  of  e 
iron,  cobalt,  or  nickel. 
When  dissolved  in  HNO3  iron  imparts  a  yellowish,  cob? 
rose,  and  nickel  an  apple  green  color  to  the  solution.  A 
tiou  of  ammonia  in  excess  gives  with  iron  a  brownish 
precipitate  of  ferric  hydroxide,  and  with  nickel  a  blue  solu 
(P-  97,  §3). 

Contains  cobalt. 
—  The  roasted 
mineral  colors 
the  borax  bead 
blue. 

Gives  sulphur  in  the  closed  tube  when  heated  in- 
tensely. Usually  reacts  for  nickel  when  fused 
with  borax  on  charcoal  (p.  98). 

Linnaeite. 

Contain  nickel. 
—  The  roasted 
mineral  colors 
the  borax  bead 
in  O.  F.,  violet 
when  hot  and 
reddish  -  brown 
when  cold. 

Give  sulphur  when  heated  intensely  in  the  closed 
tube.  ]VIillerite  occurs  usually  in  capillary 
crystals,  sometimes  in  velvety  incrustations. 

Millerite. 

Polydymite. 

In  the  HNOs  solution  ammonia  produces  an 
abundant  precipitate  of  ferric  hydroxide. 

Pentlandite. 

Contains  zinc.— 
Test  as  directed 
on  p.  131  (Fig. 
49). 

After  heating  B.  B.,  and  volatilizing  some  of  the 
zinc,  the  residue  is  slightly  fusible  and  mag- 
netic. Luster  sub-metallic. 

SPHALERITE. 

(Zinc  Blende.Blacfc 
Jack.) 

Contain  only 
iron  and  sul- 
phur. 

Give  little  or  no  sulphur  in  the.  closed  tube. 
Usually  slightly  magnetic  before  heating,  but 
sometimes  scarcely  at  all  so.  Troilite  is  found 
only  in  meteorites. 

PYRRHOTITE. 

(Magnetic  Pyrites.' 
Sometimes    nicke 
liferous. 

Troilite. 

Give  much  sulphur  in  the  closed  tube.  Are 
not  magnetic  before  heating.  Pyrite  dissolves 
completely  when  2  ivory-spoonfuls  of  its  very 
fine  powder  are  treated  in  a  test-tube  with  3  cc. 
of  concentrated  HNO3,  allowed  to  stand  until 
vigorous  action  ceases,  and  then  boiled.  Mar- 
casite  when  similarly  treated  yields  some  sep- 
arated sulphur.* 

PYRITE. 

(Iron  Pyrites.) 

MARCASITE. 

(White   Iron  Pyri 
tes.) 

*  The  nitric  acid  for  this  experiment  should  be  strong  enough  to  act  upon  powdered  p: 

DIVISION  5. — Sulphides. — Concluded  on  next  page. 


3R   SUB-METALLIC   LUSTER. 


252 


5,  or  Easily  Volatile. 
licles.  —  Continued. 

Composition. 

Color. 

Streak. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

Tet.  8ph. 
Page  183. 

Mi; 

Brass-yellow. 

Greenish- 
black. 

F.  Uneven. 

3.5 

4.2-4.3 

2 

Fe8S4. 

Bronze    to 
brass-yellow. 

Black. 

C.   Cubic,    in 
traces. 

4 

4-4.5 

2 

Isometric. 

Isometric. 
U.  mass. 

,FeS4. 

Brownish- 
bronze. 
Purplish 
tarnish. 

Grayish-black. 

F.  Uneven. 

3 

4.9-5.4 

2.5 

aS.FeS.8nSa. 

iso.  w.  Fe. 

Steel-gray. 

Black. 

F.  Uneven. 

4 

4.4 

1.5 

Massive, 

p    „                       1  Light  steel- 
Co*b"                                      gray. 

Grayish-black 

F.  Uneven. 

5.5 

4.85 

2 

Isometric. 
U.  mass. 

1,00)485.                Stool-gray. 

4.  70 

Isometric. 

AgS. 

Dark  steel- 
gray.  Dark-gray. 

F.  Uneven.         2.5-3 

6.2-6.3 

1.5 

Orthorh. 
U.  mass. 

3S. 

Steel-gray. 
Blackish        Dark-gray, 
tarnish. 

F.  Uneven. 

2.5-3 

5.7 

2-2.5 

Orthorh. 
Page  203. 
U.  mass. 

}, 

Indigo-blue.      Grayish-black. 

C.  Basal,  per. 

1.5-2 

4.6 

9  -     Hexag. 

*°    JU.  mass. 

FeaS8. 

Brownish-          B!;lck> 

bronze,  i 

C.  Basal,  per. 

1-1.5 

4.1-4.2 

1.5 

Orthorh. 

Isometric. 
Figs.      96 
and  100. 

>,Ni)8S4. 
and  Cu  iso.  v.  Co. 

Pale  steel-         iGrayish_black. 
groy.i        J 

F.  Uneven. 

5.5 

4.9 

2 

S.                            Brass-yellow. 

Black,  some- 
what greenish 

C.  Rhomboh. 
F.  Uneven. 

3-3.5 

5.65 

1.5-2 

Hex.  Rh. 

<S5. 

Light-  to 
steel-gray. 

Grayish-black. 

F.  Uneven. 

4.5 

4.8 

1.5-2 

Isometric. 

bFe)S. 

Yellowish- 
bronze. 

Black. 

Parting,  oct. 
F.  Uneven. 

3.5-4 

4.95-5.0 

1.5-2 

Isometric. 

l,Fe)S. 
pages  7  and  8. 

Dark-brown 
to  coal-black. 

Light  to  dark  - 
brown. 

C.   Dodecahe- 
dral,  per. 

3.5-4 

4.05 

5 

Iso  m.  Tet. 
Page  175. 

nSji.perbapsFeS 

iso.  w.  Fe.     Test  (o. 

7.  §  -1). 

Brownish- 
bronze. 

Black. 

Parting,  basal. 
F.  Uneven. 

4 

4.65 

2.5-3 

Hexag. 
Page  188. 
U.  mass. 

Brownish- 
bronze. 

Black. 

F.  Uneven. 

4 

4.7-4.8 

2.5-3 

Massive. 

3* 

Pale   brass  - 
yellow. 

Black,  some- 
whatbrownish. 

F.  Uneven. 

ft-6.5 

4.95-5.1 

2.5-3 

Isom.Pyr. 
Pa  gel  73. 
U.  cry  St. 

2- 

Pale-yellow  to 

almost  white. 
Yellowish 
tarnish. 

Black,  some- 
what grayish. 

F.  Uneven. 

6-6.5 

4.85-4.9 

2.5-3 

Orthorh 
Tabular, 
pyram., 

prismatic. 

energetically,  and  decompose  it  completely,  even  without  the  application  of  heat. 

(Page  253.) 

I.  MINERALS  WITH  METALLIC  OR  SUB-METALLIC   LUSTER. 

A.— Fusible  from  1-5,  or  Easily  Volatile. 
DIVISION  5.— Sulphides,  concluded. 
DIVISION  6. 


253 


I.   MINERALS   WITH   METALL 

A.— Fusible  from  1- 

Di VISION  5. — Su 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

Contain  manganese.  —  The  roast- 
ed mineral  imparts  a  reddish- 
violet  color  to  the  borax  bead 
in  O.  F. 

Gives  little  or  no  sulphur  in  the  closed  tube. 

Alabandite. 

Gives  abundant  sulphur  in  the  closed  tube. 

Hauerite. 

Contains  mere  ury.—  Gives  glob- 
ules of  the  metal  when  heated 
in  a  closed  tube  with  NaaCO3. 

in  the  closed  tube  volatile,  and  gives  a  black 
sublimate  of  HgS. 
ft^T  Compare  Cinnabar  'p.  258). 

Metacinnabarite. 

Contains  qermanium.—  When  roasted  on  charcoal,  transparent  and  white  gloDuies 
of  germanium  oxide  collect  near  the  assay,  while  farther  out  a  lemon-yellow 
coating  collects  which  has  a  peculiar  glazed  (fused)  surface. 

Argyro^ite. 

Contains  tin.—  When  fused  on  charcoal  the  globule  and  the  coal  near  it  become 
covered  with  a  coating  of  oxide  of  tin,  while  a  slight  reaction  for  germanium 
may  also  be  obtained. 

Canfieldite. 

DIVISION  6. — Not  belong 


The  native  metals.—  Most  of  them  are  malleable,  so  that 
they  can  be  beaten  out  into  sheets  by  hammering  on 
an  anvil. 

Soluble  in  boiling,  dilute] 
HNO8  (1  part  HNOs  :  2 
parts  of  water). 

After  fusing  on  charcoal  the  metal  is  bright,  and 
no  conspicuous  coating  of  oxide  is  formed  on 
the  coal.    From  the  HNO,  solution  HC1  precipi- 
tates silver  chloride.      83T"  Compare  Amalgam. 

SILVER. 

Ihe  HNO3  solution  is  made  deep-blue  by  addi- 
tion of  ammonia  in  excess. 

COPPER. 

Easily  fusible,  and  give  yellow  coatings  of  oxide 
on  charcoal.     When  heated  with    potassium 
iodide  and  sulphur  on  charcoal,  lead  gives  a 
greenish-yellow   and  bismuth  a  brilliant   red 
sublimate.     Bismuth  is  brittle. 

Lead. 

Bismuth. 

B.  B.  on  charcoal  gives  a  coating  of  zinc  oxide. 

Zinc. 

Heated  in  the  closed  tube  globules  of  mercury 
are  obtained.     Mercury  is  wholly  volatile,  and 
amalgam  leaves  a  residue  of  silver. 

Mercury. 

Amalgam. 

Insoluble  in  nitric  acid. 

Characterized    by  its  color    and    high    specific 
gravity. 

GOLD. 

Paler  color  than    gold,   and  of   lower  specific 
gravity. 

ELECTRUM. 

Oxidized  by  HNO3  yielding  a  white  residue  of 
metastannic  acid  (p.  126). 

Tin. 

Contain  iron.  —  Are  magnetic,  or 
become  strongly  so  after  heating 
T*  tt  in  R.  F. 

the  Silicates  and 
i  the  next  sections, 
te  and  Longbanite  (p. 
nay  become  slightly 
3r  heating. 

AnJiydrous.  — 
Give  little  or 
no  water   in 
the       closed 
tube. 
OEf  Compare 
Ludwigite  (p 
268). 

Strongly  magnetic  before  heating. 
|3g~  Compare  Titanic  Iron  (p.  255). 

MAGNETITE. 

(Magnetic  Iron. 

Characterized    by    its    reddish  -  brown    streak. 
Slightly  or  not  at  all  magnetic  before  heating. 

HEMATITE. 

(Specular  Iron.) 

Imparts  a  green  color  to  the  NaaCO3  bead  in  O. 
F.  (manganese}. 

Bixbyite. 

Gives  globules  of  lead  when  fused  with  Na2CO3 
on  charcoal. 

Melanotekite. 

®      ^  i  tS 

«H£  °  o 

p^~  ^  a 

Hydrous.  — 
Give  water  ir 
the       closec 
tube. 

Difficultly  fusible.      Turgite  generally  decrepi- 
tates, and  breaks  up  to  a  fine  powder  in  the 
closed  tube.     GSthite  generally  crystallizes  in 
prismatic  forms. 

TURGITE. 

(Hydro-hematit 

sis  tt> 

filfirfS 

i^iii 

GOETHITE. 

LIMONITE. 

(Brown  Hemat 

DIVISION  6.— Concluded  on  next  page. 


OR  SUB-METALLIC   LUSTER. 
.  or  Easily  Volatile, 
jades. — Concluded. 


253 


Composition. 

Color. 

Streak. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

InS. 

Iron-bhick. 
Brown  tarnish. 

Olive-green. 

C.  Cubic,  per. 

3.5-4 

3.95 

3 

Isom.  Tet. 
Cryst.  rare 

In  Sa. 

Brown    to 
brownish- 
black. 

Reddish- 
brown. 

F.  Uneven. 

4 

3.46 

3 

Isom.Pyr. 
U.  octahe- 
drons. 

IgS- 

Grayish-black. 

Black. 

F.  Uneven. 

3 

7.8 

Vol.1.  5 

Isom.  Tet. 

AgaS.Ge8g. 
Ig  iso.  w.  Ag  &  Sn  w. 
Ge. 

Black    with 
bluish  tone. 

Grayish-black. 

F.  Uneven. 

2.5 

6.26 

1.5-2 

Isometric. 
U.  mass. 

:Ag2S.(Sn,Ge)Sa. 

Black    with 
bluish  tone. 

Grayish-black. 

F.  Uneven. 

2.5-3 

6.27 

1.5-2 

Isometric. 

to  the  foregoing  divisions. 


^g. 

)ccasionally  with  Au, 
Cu,  and  Hg. 

Silver-white. 
Tarnish  gray 
to  black. 

Silver-white, 
shiny. 

F.  Hackly. 

2.5-3 

10.5 

2 

Isometric. 
U.  mass., 
acicularor 
in  plates. 

>ll. 

Copper-red. 

Tarnish  black. 

Copper-red, 
shiny. 

F.  Hackly. 

2.5-3 

8.85 

3 

Isometric. 
U.  mass. 

>b. 

Lead-gray. 

Lead-gray, 

shiny. 

F.  Hackly. 

1.5 

11.37 

1 

Isometric. 

M. 

Silver-white. 

Silver-white, 
shiny. 

C.    Basal    and 
r  horn  boh  e- 
dral,  per. 

2-2.5 

9.8 

1 

Hex.  Rh. 
U.  gran. 

Sn. 

Grayish-white. 

Grayish-  white, 
shiny. 

C.  Basal,  per. 

2 

7.0 

1.5 

Hex.  Rh. 

Ig- 

Tin-  white. 

13.6 

Liquid. 

ig  with  Ag. 

Silver-white. 

Silver-white, 
shiny. 

F.  Uneven. 

3-3.5 

13.7- 

14.1 

Isometric. 

lu,     always    with 
some  Ag. 

Gold-yellow. 

Gold-yellow, 
shiny. 

F.  Hackly. 

2.5-3 

19.3 
when 
pure. 

2.5-3 

Isometric. 
U.  mass. 

iu  with  much  Ag. 

Yellowish- 
white. 

Yellowish- 
white,  shiny. 

F.  Hackly. 

2.5-3 

13-16 

2-2.5 

Isometric. 

3n. 

Tin-white. 

Tin-white, 
shiny. 

F.  Hackly. 

2 

7.2 

1 

?e304  = 
FeO  +  Fe203. 

Iron-black. 

Black. 

F.  Uneven. 
Parting  oct. 

6 

5.18 

5-5.5 

Isometric. 

e\32o3. 

Dark      steel- 
gray  to  iron- 
black. 

Dark  reddish- 
brown,  Indian- 
red. 

F.  Uneven. 
Parting  rhom- 
bohedral. 

5.5-6.5 

5.20 

5-5.5 

Hex.  Rh. 
Page  194. 

FeMnOs  = 
FeO.MnO2. 

Black. 

Black. 

F.  Uneven. 

6-6.5 

4.94 

4.5 

Isometric. 

;Fe"/403)Pb3(Si04)3 

Dark  brown  to 
black. 

Yellowish  - 
brown. 

F.  Uneven. 

5-5.5 

5.85 

2-2.5 

Orthorh. 
Prismatic. 

Fe4O5(OH)2  = 
2Fe2O3  -f  H2O. 

Reddish-black 

Dark   reddish- 
brown. 

F.  Splintery. 

5.5-6 

4.14 

5-5.5 

Botryoid. 
lacrust. 

FeO(OH)  = 
2FeaO3  +  2H2O. 

Dark-  brown  to 
black. 

Yellowish  - 
brown. 

C.  Pinac.,  per. 

5-5.5 

4.35 

5-5.5 

Orthorh. 

Fe4O3(OH)6  = 
2Fe2O3  -f  3H2O. 

Dark-brown  to 
black. 

Yellowish  - 
brown  . 

F.  Splintery. 

5-5.5 

3.6-4.0 

5-5.5 

Botryoid. 
Stalactitic 

(Page  254.) 
I.  MINERALS  WITH   METALLIC  OR  SUB-METALLIC   LUSTER. 

A.— Fusible  from  1-5,  or  Easily  Volatile. 
DIVISION  6,  concluded. 


254 


I.   MINERALS  WITH   METALLI 

A.— Fusible  from  1— 

DIVISION  6. 


General  Characters. 


Specific  Characters. 


"Silicate*.  —  Ilvaite  and  Allauite 
are  decomposed  by  HC1,  and 
yield  gelatinous  silica  upon 
evaporation.  Neptunite  is  in- 
soluble in  HC1,  but  may  be 
tested  for  a  silicate  as  directed 
on  p.  110,  §4. 

U.B.  —  These  silicates  have  a 
pitchy  or  resinous  luster,  and 
they,  as  well  as  others  which 
are  black  owing  to  the  presence 
of  iron,  are  more  proper!} 
classified  in  subsequent  sec- 
tions  under  minerals  without 
metallic  luster. 

|^"  Compare  Melanotekite,  Ken- 
trolite,  and  Braunite,  of  this 

division. 

Contain  tungsten.  —  Fuse  with 
]<ra2COs,  pulverize  the  fusion, 
digest  with  boiling  water,  and 
filter.  The  filtrate  made  acid 
with  HC1  and  boiled  with  tin 
assumes  a  blue  color  (p.  129 
4  2). 

The  high  specific  gravity  is 
noticeable.  


ntuuiesces    slightly  when    fused    B.   B.      The 
"  icidedl 


globule  is  decidedly  magnetic. 


Intumesces  strongly  when  fused  B.  B.  The 
globule  is  sometimes  magnetic.  Gives  reactions 
for  the  rare-earth  metals  (p.  65). 


Fuses  B.  B.  to  a  black  globule  and  colors  the 
flame  yellow.  Reacts  for  titanium  when  tested 
as  directed  on  p.  127,  §2. 


Name  of  Species. 


Ivaite. 
(Lievrite.) 


Allanite. 


Neptunite. 


Imparts  to  the  Na2CO3  bead  in  O.  F.  a  green 
color  (manganese).  Fused  on  charcoal  with  a 
little  Na2CO3  yields  a  magnetic  mass. 


WOLFRAMITE. 

Compare     hiibnt 
ite,  p.  283. 


Contains  little  or  no  manganese.     Fusible  B.  B 
to  a  magnetic  mass. 


Contain  niobium.—  Fused  with 
borax,  then  dissolved  in  HC1 
and  boiled  with  tin,  the  solu- 
tion nssumes  a  blue  color  (p. 
99,  §1). 

The '  high  specific  gravity  is 
noticeable. 


React  for  uranium  and  the  rare-earth  metals 
when  tested  as  directed  on  p.  129,  §  2,  and  p 
65. 


Contain  copper.— ~B.  B.  alone,  or 
with  NaaCO3,  on  charcoal,  give 
a  globule  of  copper.  Aftei 
moistening  with  HC1  impar 
azure-blue  and  green  colors  t( 
the  blowpipe  flame  (p.  72,  §  1) 


Contains  lead.—  With  Na2CO3  OD 
charcoal  gives  globules  of  th 
metal  and  a  coating  of  lea 
oxide. 


Reinite. 


ieacts  for  iron  and  usually  also 
when  +°ctf>c\  n«  Hlrftftted  abo1 


[Or    I/TV  ft    »UU     UBUCMJJ     uaovy     *.      i     ••- *     . 

tested  as  directed  above  for  wolframite. 


Characterized  by  its  sub-metallic  luster  and  re 
streak  (see  p.  263).  


Tenorite  crystallizes -in  scales;  paramelaconite  i 


prisms. 


Wolframite,  in  par 


COLUMBITE. 


Samarskite. 


Aannerodite. 
(Onnerodite.) 


CUPRITE. 


Tenorite. 
(Melaconite.) 


Paramelaconite. 


When  heated  in  the  closed  tube  yields  tusiDie 
lead  oxide  and  oxygen  gas.  Test  as  directed  on 
p.  100,  §  1. 


Plattnerite. 


Imparts  a  reddish-violet  color  to  the  borax  bead 
in  O.  F.  (manganese).     Compare  Melanotetote. 

HCK 


Kentrolite. 


Contain  manganese,  but  do  not 
give  the  reactions  of  the  fore- 
«roing  sections.— Impart  to  the 
borax  bead  in  O.  F.  a  reddish- 
Tiolet  color. 


The    fine    powder    is    slowly    soluble    in 
Yields  a  small  amount  of  gelatinous  silica  o: 
evaporation. 


Gives  a  slight  coating  of  oxide  of  antimony  when 
heated  with  NaaCO3  on  charcoal. 


Braunite. 


Laangbanite. 
(Longbanite.) 


OR  SUB-METALLIC   LUSTER, 
or  Easily  Volatile. 

oncluded. 


254 


Composition. 

Color. 

Streak. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

iFe"2(Fe'".OH) 
(Si04)a. 

Iron-black. 

Black. 

F.  Uneven. 

5.5-6 

4.05 

2.5 

Orthorh. 
U.  prism. 

"a(R"'.OH)R'"9 

(Si04)3. 

'=Ca  and  Fe. 
'"=A1.   Fe,    Ce,    La, 
and  l>i. 

Brown  to 
pitcb-black. 

Gray. 

F.    Uneven   to 
conchoidal. 

5.5-6 

3.5-4.2 

2.5 

Monocl. 
U.  mass. 

Sa,K)(Fe,Mn) 
TiSi4O12. 

Black. 

Cinnamon- 
brown. 

C.  Prismatic. 
F.  Conchoidal. 

5-6 

3.23 

3-4 

MonocL 

Fe,Mu)WO4. 

Black. 

Black. 

C.  Pinac.,  per. 
F.  Uneven. 

5-5.5 

7.2-7.5 

3-3.5 

Monocl. 
U.  crysk 

Monocl. 

^eW04. 

Black. 

Black. 

C.  Pinac.,  per. 

5-5.5 

7.2-7.5 

3-3.5 

?eW04. 

Blackish- 
brown. 

Brown. 

F.  Uneven. 

4 

6.64 

3-3.5 

Tetrag. 

Fe,Mn)(Nb,Ta)2O6. 

Iron-black. 

Black. 

F.  Uneven. 

6 

5.3-7.0 

5-5.5 

Orthorh. 
U.  cryst. 

R"3R'"2(Nb,Ta)6021 
i"=Fe,  Ca.  U02: 
ci"/=Ce  and  Y  earths. 

Velvet-black. 

Dark    reddish- 
brown. 

F.  Conchoidal. 

5-6 

5.6-5.8 

4.5-5 

Orthorh. 
U.  mass. 

Uncertain. 
Nb,  U,  Y.  Th,  Ce,  Pb, 
Fe,  Ca,  H,  O. 

Black. 

Brown    to 
blackish 
brown. 

F.  Uneven. 

6 

5.7 

4.5 

Orthorh. 

Cu2O. 

Deep-red. 

Brownish-red, 
Indian-red. 

F.    Conchoidal 
or  uneven. 

3.5-4 

6.0 

2.5-3 

Isometric. 
CU.p.219 

OuO. 

Steel-  to   iron- 
gray. 

Grayish-black. 

C.  Basal,  per. 
F.  Uneven. 

3-4 

5.8-6.2 

3 

Monocl. 
Massive. 

CuO? 

Purplish-     to 
pitch-black. 

F.  Uneven. 

5 

5.83 

3 

Tetrng. 

Pb02. 

Iron-black. 

Chestnut- 
brown. 

F.  Uneven. 

5-5.5 

8.5 

1.5 

Tetrag. 
U.  mass. 

lMn'"40,)Pb, 
(Si04)3. 

Fe  iso.  w.  Mn. 

Black. 

Brown. 

F.  Uneven. 

5-5.5 

6.19 

2-2.5 

Orthorh. 

MnMnOg     with     a 
little  MnSiO3. 

Black. 

Brownish- 
black. 

C.  Pyramidal. 
F.  Uneven. 

6-6.5 

4.8 

4.5-5 

Tetrag. 
Fig.  143, 
page  178. 

Uncertain. 
Mn,  Fe,  Si,  and  Sbjlron-black. 
oxides. 

Dark   reddish- 
brown. 

F.  Uneven. 

6.5 

4.92 

4.5 

Hex.  Rh. 

(Page  255.) 
I.  MINERALS   WITH   METALLIC  OR  SUB-METALLIC  LUSTER. 

B.— Infusible  or  Fusible  above  5,  and  Non- volatile. 
DIVISION  1.— Iron  Compounds. 


•255  I.   MINERALS   WITH   METALL: 

B.— Infusible,  or  Fusible 
DIVISION  1. — Iro'n  Compounds. — Strongly  attracted  by  a  magnet  after  being  heated  befor 

N.B. — The  minerals  in  this  division  are  chiefly  the  oxides  and  hydroxides  of  iron.     Several  of  t: 
slowly.     The  solutions,  after  dilution  with  water,  may  be  tested  for  ferrous  and  ferric  iron  with  pc 


General  Characters. 


Specific  Characters. 


Name  of  Species. 


Strongly  magnetic  without  heat- 
ing.    Malleable. 

Compare  platinum  (p.  257). 


Wheii  treated  as  directed  on  p.  97,  §4,  meteoric! 
iron  has  always,  and  terrestrial  irons  have  often,;lr°jj'eteoric  Iron 
reacted  for  nickel. 


Characterized  by  containing  much  nickel. 


Very  slowly  attacked  by  HC1. 
Reacts  for  titanium  (p.  127,  §  2). 


Strongly  magnetic  without  heat 
ing.     Brittle. 


The  fine  powder  is  slowly,  but  completely,  solu- 
ble in  HC1.  The  solution  reacts  for  both  fer- 
rous and  ferric  iron.  Fus.  =  5-5.5. 


Reacts  for  magnesium  when  tested  as  directed  on 
p.  91,  §1.  b. 


Contains  titanium. — After  fusion 
with  NaaCOs  the  material  can 
be  dissolved  by  HC1,  and  ttie 
solution  when  boiled  with  tin 
becomes  violet  (p.  127,  §  2). 


Gives  a  coating  of  oxide  of  antimony  when  fused 
with  NaaCO3  on  charcoal. 


Distinguished    by  differences  in  crystallization 
and  physical  properties. 


Awaruite. 


ILMENITE     (Titan 
Iron,  in  part.) 


MAGNETITE. 


Magnesioferrite. 


Derbylite. 


ILMENITE. 

(Titanic  Iron.) 


Pseudobrookite. 


Contain   manganese. — Impart  to 
the  Na2CO3  bead  in  O.  F. 
green  or  bluish-green  color. 


Gives  a  coating  of  oxide  of  zinc  when  the  very 
fine  powder,  mixed  with   a   little   Na2COs,  is  FRANKLINITE. 
heated  intensely  on  charcoal. 


a  Gives  a  coating  of  oxide  of  antimony  when  treated 
as  above. 


Melanostibian. 


Does  not  give  the  foregoing  reactions. 


Jacobsite. 


Water  about  5$.     Generally  decrepitates  violent- 
ly when  healed  in  the  closed  tube. 


Turgite 

(Hydro-hematite 


Give  water  in  the  closed  tube. 
Difficultly  fusible.  Fus.  = 
5-55. 


Water  about 
prisms. 


Generally  crystallized    in 


GOETHITE. 


Water  about  15$.  Mammillary  and  stalactitic 
(p.  222).  Often  impure.  Distinct  crystals  un- 
known. 


LIMONITE. 
(Brown  -Hematit 


Give   little  or  no  water  in  the 

closed  tube. 
Daubreelite  reacts  for    sulphur 

when  roasted  in  an  open  tube. 
E3g*Compare  Tripuhyite  (p.  263). 


Streak  brownish-red  (Indian-red,  red-ocher). 
Sometimes  slightly  magnetic  before  heating. 
Fus.  =  5-5.5. 


HEMATITE. 

(Specular  Iron.) 


Imparts  a  green  color  to  the  salt-of-phosphorus  Daubr6elite. 
bead  (chromium}.     Compare  Cliro'mi'e  (p   256). 


(Meteoric  only.) 


OR   SUB-METALLIC   LUSTER. 


255 


x>ve  5,  and  Non-volatile. 

ie  blowpipe  in  the  reducing  flame  (the  test  must  not  be  made  while  the  fragment  is  hot,  p.  84,  §  1). 

ii  are  important  as  ores  of  the  metal.     Generally  they  dissolve  in  hydrochloric  acid,  though  often 
sium  ferri-  and  f errocyanides,  as  directed  on  pi  85,  §  4. 


Composition. 

Color.                    Streak. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Crystalli- 
zation. 

re,  also  Fe  with  Ni. 

Steel-gray. 

Steel-gray. 

C.  Cubic. 
F.  Hackly. 

4-5 

7.3-7.5 

Isometric. 
U.  mass. 

'eNia. 

Steel-gray.         Steel-gray. 

F.  Hackly. 

5 

8.1 

Massive. 

eTiO3    with     FeaO8     in 
varying  proportions. 

Iron-black.        Black. 

F.  Uneven. 

5.5-6 

4.7-5.1 

Hex.  Rh. 
U.  mass. 

1e3O4=FeO.Fe203. 

Iron-black. 

Black. 

Parting  octa- 
hedral. 
F.  Uneven. 

6 

5.18 

Isometric. 
Figs.     96, 
97  &  102. 

lgFeaO4=MgO.FeaO3. 

Iron-black.         Black. 

F.  Uneven. 

6-6.5 

4.6 

Isometric. 

FeTiO3.FeSb2O6. 

Pitch-black.     JBrown. 

F.  Conchoidal. 

5 

4.53 

Orthorh. 

Hex.  Rh. 
Page  197. 

VTiO3=FeO.TiOa. 

[%  iso.  w.  Fe. 

Iron-black. 

Black. 

F.  Uneven. 

5.5-6 

4.7 

\>4(TiO4)3. 

Brownish- 
black. 

Yellowish-    or 
reddish-brown 

F.  Uneven. 

6 

4.98       lOrthorh. 

Fe,Zn,Mn)O.(Fe,Mn),Os. 

V8O4  with  Zn  and  Mn  iso.w.Fe 

Iron-black. 

Dark-brown. 

F.  Uneven. 

6 

5.15 

Isometric. 
Figs.      96 
and  102. 

(Fe,Mn)O.Sb2O8. 

Black. 

Cherry-red. 

C.  Two  direc- 
tions, 90°. 

\ 

Orthorh.? 

Mn,Mg)O.(Fe,Mn)aO3. 

Black. 

Brownish- 
black. 

F.  Uneven. 

6 

4.75 

Isometric. 

^e4O5(OH)a=2FeaO3.Had 

Black   to  red- 
dish-black. 

Brownish-red, 
Indian-red. 

F.  Splintery. 

5.5-6 

4.14 

Massive. 
Mammill. 

^eO(OH)=2Fe2O3.2HaO. 

Dark-brown  to 
black. 

Yellowish- 
brown, 
yellow-ocher. 

C.   Pinacoidal, 
perfect. 

5-5.5 

4.35 

Orthorh. 
Prismatic. 

re4Os(OH).= 
2FeaOs.3H20. 

Dark-brown  to 
nearly  black. 

Yellowish- 
brown, 
yellow-ocher. 

F.  Splintery. 

5-5.5 

3.6-4.0 

Orthorh. 
U.  fibrous. 

^ea03. 

Steel-gray      to 
iron-black. 

Brownish-red. 
Indian-red. 

F.  Uneven, 
scaly,  fibrous. 

5.5-6.5 

.9ft        Hex.  Rh. 
Page  194. 

^S.CraSs. 

Black. 

Black.               JC.  One  direc. 

K  /v,         Massive. 
Scaly.  _ 

(Page  256.) 

I.  MINERALS   WITH   METALLIC  OE  SUB-METALLIC  LUSTER. 

B. — Infusible,  or  Fusible  above  5,  and  Non-volatile. 
DIVISION  2. — Manganese  Compounds. 

DIVISION  3,  in  part. 


S56 


I.   MINERALS   WITH   METALLL 


B.— Infusible,  or  Fusible 

DIVISION  2  -Manganese  Compomids.-A  trifling  quantity  of  the  material  will  impar 
which  manganese  compounds  impart  to  the  sodium-carbonate  bead  in  the  oxidizing  flame  is  also  a 

N.B.-The  minerals  in  this  division  are  chiefly  oxidts  of  manganese.  They  dissolve  in  hydrc 
heated  in  a  closed  tube  (p.  100,  §  1). 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

Give   little  or   no  water   when 
heated  in  the  closed  tube. 

|^-   Ompare     rinakiolite    (p. 
277). 

Contains  copper,  and  imparts  to  the  blowpipe 
flame  a  blue  or  green  color  after  moistening 
with  HC1. 

Crednerite. 

Reacts  for  titanium  when  tested  as  directed  on  p. 
129,  §2. 

Pyrophanite. 

Give  oxygen  gas  when  heated  in  the  closed  tube 
(p.  100,  §  1).  Pyrolusite  is  perhaps  always  a 
pseudomorph  after  other  minerals  (often  after 
manganite).  It  is  soft,  and  contains  about  2 
per  cent  of  water. 

Polianite. 

PYROLUSITE. 

Do  not  give  oxygen  gas  when  heated  in  the  closed 
tube  (p.  100,  §  1).  Finely  pulverized  braunite 
is  slowly  decomposed  by  HC1,  and  the  solution 
yields  gelatinous  silica  upon  evaporation. 

Braunite. 

Hausmannite. 

Give  much  water  when  heated  in 
the  closed  tube. 

igT"  Compare  Asbolite  and  Wad 
(p.  292). 

The  prismatic  crystallization  and  dark-  brown 
streak  are  characteristic.  Compare  Pyrolusite. 

MANGANITE. 

B.  B.  on  charcoal  gives  a  coating  of  oxide  of 
zinc. 

Chalcophanite. 

Does  not  crystallize.  The  HC1  solution  generally 
gives  a  white  precipitate  of  barium  sulphate 
upon  addition  of  HaSO4. 

PSILOMELANE. 

DIVISION  3.— Not  belong 


Very  soft.    Readily  mark  paper 
and  soil  the  fingers. 

Heated  B.  B.  in  the  forceps  colors  the  flame 
yellowish-green.  Roasted  in  the  open  tube 
gives  the  reactions  for  a  sulphide  and  for 
molybdenum  (p.  95). 

MOLYBDENITE. 

Does  not  give  the  foregoing  reactions.  Very  re- 
fractory. 

GRAPHITE. 

(Black  Lead.) 

Contains  chromium. — Imparts  a 
green  color  to  the  borax  and 
salt  of  phosphorus  beads. 


Finely  powdered  chromite  mixed  with  NaaCO3,  |CHROMITE. 
in  equal  proportions,  and  intensely  heated  on     (chromic  I 

T-  .       *      .      *  1      •        I.       '-.       „  4  t  «.-*  rf-»4-y^y-l       Y\ir     O 


111       ttjUlll        plUpUl  L1V110,      OAJV*       AJ-»W~~--^         -       -IV. 

charcoal,  gives  a  mass  which  is  nttracted  by  a 
magnet  (iron).     Magnesiau-chromite  may  con- 


nijiguci  (vrvnit     J.?I.U^UCOIC*LI-^-      >•««...—   — ./    - 
tain  too  little  iron  to  give  the  ^oregoingreacnon. 


Irou.) 


Magnesian-chrom: 


3. — Concluded  on  next  page. 


OR   SUB-METALLIC   LUSTER. 


256 


>ove  5,  and  Non-volatile. 

the  borax  bead  in  the  oxidizing  flume  a  reddish-violet  or  amethystine  color.      The  green  color 
y  delicate  and  decisive  test. 

oric  acid  with  evolution  of  chlorine  gas  (p.  101,  §  2),  and  many  of  them  yield  oxygen  gas  when 


Composition 

Color. 

Streak. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Crystalli- 
zation. 

u8Mn<O». 

Iron-black, 

Brownish- 
black. 

C.  Basal,  per. 

4.5 

4.98 

Monocl. 
Foliated. 

InTiOs  —  MnO.TiO2. 

Deep-red. 

Ocher-yellow. 

C.  lihoinbohe- 
dral,  per. 

5 

4.54 

Hex.  Rh. 

Cl.  14.  p.  219. 

InO2. 

Steel-gray. 

Black. 

C.  Prismatic, 
perfect. 

6-6.5 

5.0 

Tetrag. 

itiiO2  with  about  2#H2O. 

Iron-black. 

Black. 

F.  Splintery. 

2-2.5 

4.75 

Massive. 
Pseudom. 

klnMnOs  with   a   little 
MnSiO3 

Black. 

Brownish- 
black. 

C.  Pyramidal. 
F.  Uneven. 

6-6.5 

4.8 

Tetrug. 
Fig.  143. 

tfn3<X 

Black. 

Chestnut- 
brown. 

C.  Basal. 
F.  Uneven. 

5-r>.5 

4.8 

Tetrag. 

KnO(OH)  =  Mn2O3.H2O. 

Steel-gray     to 
iron-black. 

Dark-brown. 

(J.  Pinacoidal, 
perfect. 

4 

4.31 

Orthorh. 
Prismatic. 

Mn,Zn)Mu2O6.H2O. 

Bluish-black. 

Dark       choco- 
lute-brown. 

0.  B<isal,  per. 

2.5 

4.0 

Hex.  Rh. 

Uncertain. 
VlnO-,  with  MnO,  H2O, 
and  often  BaO  and  K2O. 

Iron-black. 

Brownish- 
black. 

F.  Uneven. 

5-6 

About 
4.3 

Massive. 

to  the  foregoing  divisions. 


MoS2. 

Lead-  gray. 

Grayish-black. 

C.  Basal,  per. 

1-1.5 

4.75 

Hexag.? 

Foliated. 

C. 

Iron  black. 

Black. 

C.  Basal,  per. 

1-1.5 

2.20 

Hex.  Rh. 

Foliated. 

Essentially  FeCr2O4  = 
FeO.Cr2O3. 

Iron-black     to 
brownish- 
black. 

Dark-brown. 

F.  Uneven. 

5.5 

4.6 

Isometric. 
U.  mass. 

FeCr2O4  with  MgAl2O4. 

Brownish- 
black. 

Brown. 

F.  Uneven. 

5.5 

4.2 

Isometric. 
U.  mass. 

(Page  257.) 

I.  MINEEALS  WITH  METALLIC   OK  SUB-METALLIC  LUSTER 

B.— Infusible,  or  Fusible  above  5,  and  Non-volatile. 
DIVISION  3,  concluded. 


1.  MINERALS  WITH  METALI 

B.— Infusible,  or  Fusibl 

DIVISION 


General  Characters. 


Contain  titanium.— Fused  with 
borax,  then  dissolved  in  HC1 
and  boiled  with  tin,  the  solu- 
tion becomes  violet  (p.  127,  §  2). 

ISPCompare  Rulile,  OctaJiedrite, 
and  Brookite  (p.  299),  which 
sometimes  are  black  and  have 
a  sub-metallic  luster. 


Specific  Characters. 


After  the  violet  color  of  titanium  has  been  ob 
taiued,  by  continued  boiliug  with  tin  the  solu 
tiou  finally  assumes  a  blue  color  (niobium,  p 


Compare  Polymignite,  below. 


Fused  with  the  acid  sulphate  of  potash  and 
fluorspar  mixture,  momentarily  colors  the  flame 
green  (boron).  Fus.  =  5.5 


A  little  of  the  fine  powder  mixed  with  an  equa 
volume  of  Na2CO3  and  fused  intensely  in  char 
coal  gives  a  mass  which  is  attracted  by  a  mag 
net  (see  p.  255). 


After  fusing  with  Na2CO3  and  dissolving  in 
HC1  the  titanium  may  be  precipitated  by  am- 
monia. In  the  filtrate  calcium  may  be  detect- 
ed by  ammonium  oxalate,  and  magnesium  by 
sodium  phosphate. 


Name  of  Species 


Dysanalyte. 


Warwickite. 


ILMENITE. 

( Magn  esian  Variet 


Pseudobrookite. 


Perovskite. 
(Perofskite.) 


leikielite. 


Contain  niobium. — Fused  with 
borax,  then  dissolved  in 
and  boiled  with  tin,  the  solu- 
tion assumes  a  blue  color  (p. 
99,  |  1).  The  high  specific 
gravity  is  noticeable. 

Compare  the  difficultly 
fusible  niobium  minerals  on  p. 
254,.  and  those  with  resinous 
to  sub-metallic  luster  on  pp. 
298  and  300. 


renerally  imparts  to  the  Na2CO3  bead  in  O.  F.  a 
green  color  (manganese).  Fused  on  charcoal 
with  a. little  Na2CO3  yields  a  magnetic  mass. 
For  variations  in  specific  gravity  see  p.  7. 


COLUMBITE. 


Mossite. 


In  making  the  reduction  test  with  zinc  the 
violet  color  of  titanium  appears  before  the  blue 
of  niobium  (p.  99,  §2). 


'olymignite. 


Contain  tantalum  (p.  123),  but 
give  no,  or  only  slight,  reac- 
tions for  niobium.  Character- 
ized by  exceptionally  high 
specific  gravity. 


React  for  iron  and  sometimes,  also,  for  manga- 
nese when  te&ted  as  directed  above  for  colum- 
bite. 


rantalite. 


?apiolite. 


Gi-ive  reactions  for  tin  and  uranium  when  tested 
as  directed  on  pp.  126,  §  3,  and  129,  §  2. 


Hielmite. 


Contains  uranium. — Imparts  to 
the  salt  of  phosphorus  bead 
in  O.  F.  a  yellowish-green  and 
in  R.  F.  a  green  color. 


Soluble  in  dilute  H2S04  with  the  slight  evolution 
of  a  gas  (helium).  The  high  specific  gravity  is 
noticeable. 


Jraniniie. 

Pitch  Blende.) 


Compare    Baddeleyite,  ZrO2  (p. 


3addeleyite. 


Contain  platinum  or  the  metals 
of  the  platinum  group  (pp.  103 
and  104). — These  minerals  are 
characterized  by  exceptionally 
high  specific  gravities,  and  by 
their  insolubility  in  any  single 
acid. 


Gives  sulphur  dioxide  when  roasted  in  the  open 
tube,     fl^g*  Compare  Sperrylite,  p.  247. 


Laurite. 


Malleable, 
netic. 


B.  B.   unaltered.     Sometimes  mag 


'latinum. 


Malleable.  Loses  its  tarnish  when  heated  B.  B. 
in  R.  F.,  but  regains  it  by  heating  in  the  open 
tube. 


Palladium. 


Slightly  malleable  to  brittle.    Heated  in  the  open 
tube  gives  the  odor  of  osmium  oxide. 


ridosmine. 


Does  not  react  for  osmium. 


ridium. 


OR  SUB-METALLIC   LUSTER, 
oo ve  5,  and  Non-volatile. 

-Concluded. 


25? 


Composition. 

Color. 

1 
Streak. 

Cleavage  and 
Fracture 

Hard- 
ness. 

Specific 
Gravity. 

Crystalli- 
zation. 

'uTiO3,  with  some 
(Fe.Ca)Nb2Ofi  and  rare- 
earih  metals.      Formula 
uncertain. 

Black. 

Gray. 

C.  Cubic. 
F.  Uneven. 

5-6 

4.18 

Isometric. 
Cubes  & 
Octahe- 
d  rons. 

Mg,Fe)4B2TiO9? 

Dull-black. 

Black. 

C.    One  direc- 
tion, per. 
F.  Uneven. 

3-4 

3.35 

Orthorh. 
Prismatic. 

Mg,Fe)Ti03  = 
(Mg,Fe)O.TiO3. 

Ton-black. 

Black. 

F.  Uneven. 

5.5-6 

4.30 

Hex.  Rh. 

Page  197. 

?e4(TiO«)8. 

3rownish- 
black. 

Yellowish-     or 
reddish-brown 

F.  Uneven. 

6 

4.98 

Orthorh. 

VTiOg. 

Brown  to 
black. 

Grayish. 

F.  Uneven. 

5.5 

3.95 

Isometric. 

tfgTiOs. 
"e  iso.  w.  Mg. 

Blue-black. 

C.  Perfect. 

6.5 

3.98 

Hex.  Rh.? 

2ssentially(Fe,Mn)NbaO«, 
with  (Fe,Mu)Ta2O6. 

Black. 

Dark  -  red     to 
black. 

F.  Uneven. 

6 

5.3-6.5 

Orthorh. 
U.  prism. 

?e(Nb,Ta)aO6. 

Black. 

Black. 

F.  Uneven. 

6 

6.45 

Tetrag. 

Jncertain. 
^b,  Zr,  Ti,  Ca,  Th,  Ce,  Y, 

Fe'",  Fe",  O. 

Black. 

Dark-brown. 

F.  Conchoidal. 

6.5 

4.8 

Orthorh. 

Fe,Mn)Ta2O6. 

Jb  iso.  \v.  Ta. 

Black. 

Black. 

F.  Uneven. 

6 

6.5-7.3 

Orthorh. 

^eTa.Oe. 
v'b  iso.  w.  Ta. 

Black. 

Black. 

F.  Uneven. 

6 

7.3-7.8 

Tetrag. 

Jncertain. 
:a,  Nb,  Sn,  U,  Y,  Ce,  Fe",  Mn, 
Ca,  Ti,  0. 

Black. 

Grayish  black. 

F.  Uneven. 

5 

5.8 

Orthorh. 

Jncertain. 
JO3,  UO2,  Th,  Y,  Pb,  and 
He. 

Black. 

Brownish- 
black. 

F.  Uneven. 

5.5 

9-9.7 

Isometric. 
U.  mass. 

5r02. 

luS8. 

>s  iso.  w.  Ru. 

Iron-black. 

Dark-gray. 

C.  Octahedral. 
F.  Conchoidal. 

7.5 

7.0 

Isometric. 

)t,  with  Fe  and  the  rare 
platinum  metals. 

Whitish  steel- 
gray. 

Gray,  shiny. 

F.  Hackly. 

4-4.5 

14-19 

Isometric.. 

M,  with  Pt  and  Ir. 

Whitish   steel- 
gray. 

Gray,  shiny. 

F.  Hackly. 

4-4.5 

11.3- 
11.8 

Isometric, 

[r,  with  Os,  Rh,  and  Pt. 

Tin-white. 

Gray. 

C.  Basal,  per. 

6-7 

19-27 

Hex.  Rh. 

!r,  with  Pt. 

Tin-white. 

Gray. 

F.  Hackly. 

6-7 

22.7 

Isometric. 

(Page  258.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER, 
A. — Easily  Volatile  or  Combustible. 


B     The  few  minerals 


II.   MINERALS  WITHO 
A.—  Easily  Volati 
are  included  in  this  section  entirely 


Knd  The  sublimate  in  the  closed  tube  is  a  red  to  dark 


Burns  with    »    K,*-~   

gives  the  strong  odor  of  sul- 
phur dioxide. 


yellow  liquid 
when  cold 


solid  SULPHUR. 


Contain  arsenic.— Yield  the  vol- 
atile, crystalline  sublimate  ol 
arsenious  oxide  when  heated  in 
the 

carefully ).  An  arsenical  mirror 
may   be  obtained    by    mixing 


flame  (thallium). 


green  color  to  the  blowpipe 


"s?.B^^^AS^^AS»& 

"  •••  transparent  solid  when  cold.  


may   be  obtained    oy   mixing  - 

the  mineral  with  six  volumes  yield  tbewhite  crystalline  sublimate 5  of  arsenious 

of    dry   Na2CO3   and   a   little     oxi(}e  when  heated  in  a  closed  tube.     Volatile 

•^    i  _j ,,«^       l»^r»tir%n-  i  -i»   -Li.    4-n«  ^-1  S\W\S*-*T   t  f\     "filCP 


\/L  Vi.lJ'  •»^**»^^^ 

charcoal  powder  and  heating 
in  a  closed  tube  (p.  51.  §1 


Contain  antimony.  —  B.  B.  on 
charcoal  fuse  and  coat  the 
coal  with  a  dense  white  subli- 
mate of  the  oxides  of  anti- 
mony. 


In  the  open  tube  gives  sulphur  dioxide. 


with  only  a  slight  tendency  to  fuse. 


Fuse  easily  when  heated  in  the  closed  tube,  and 
Hve  a  slight  white  sublimate  consisting  oftei 
of  prisms  and  octahedrons  of  Sb2O3. 


Contaia    ammonium  -Give    the  Volatile  without  (,,-ion     Jhe  ^ueous  solution 


UllUllll         tt//fr/« c/v^vw*'*  -"  -       — 

odor  of  ammonia  when  heated 
in  a  closed  tube  with  lime  (ig- 
nited calcite),  or  boiled  in  a 


gives  a  precipitate  with  silver  nitrate. 


test  -  tube 
hydroxide. 


with     potassium 


Fusible.     The  aqueous  solution  gives  a  precipi 
tate  with  barium  chloride. 


Contain  mercury.—  Give  a  subli- 
mate of  mercury  when  heated 
in  a  closed  tube  with  dry 
sodium  carbonate  (p.  94,  §  1). 


Streak  red.  Gives  sulphur  dioxide  and  mercur 
in  the  open  tube  (p.  94,  §  2).  Gives  a  blac 
sublimate  (HgS)  in  the  closed  tube. 


Contains  lead.— Gives  a  globule 
of  the  metal  and  a  coating  of 
oxide  when  fused  with  Na2CO 
on  charcoal. 


Contain  sodium  or  potassium. — 
Color  the  blowpipe  flame  yel 
low  or  violet,  respectively. 


After  testing  for  the  mercury  with  Isa2CO3,  th 
contents  of  the  tube,  when  dissolved  in  wate 
and  HN03,  will  give  a  precipitate  with  silve 
nitrate. 


orandite. 


EALGAR. 


RP1MENT. 


rsenolite. 


laudetite. 


<ermesite. 


Senarmoniiie. 


Valentinite. 


Sal-ammoniac. 


Mascagnite. 


CINNABAR. 


Calomel. 


*  Quite   soluble   in   hot  water, 
solution  deposits  lead  chloride 


On  cooling,   the 


After  ignition  B.  B.  the  residue  imparts  an  alka- 
line reaction  to  turmeric  paper. 


Cotunnite. 


A  number  o 
will  be  fo\ 


C   METALLIC   LUSTER. 
or  Combustible. 


larcoal. 


258 


.,  ,               

Composition. 

.  —  — 
Color. 

—  —  —  — 
Luster. 

.      — 

Cleavage  or 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
ility. 

Crystalli- 
zation. 

, 

Pale  yellow. 

iesinous. 

.  Conchoidal 
or  uneven. 

.5-2.5 

2.07 

1 

rthorh. 
age  202. 

flAsS,  =   g  AgA  , 

Carmine-red. 

Adamantine. 

.   One    direc- 
tion, perfect. 

2.5 

5.53 

1 

Vlonocl. 

US. 

iurora-red. 

Resinous. 

.  Pinacoidal. 
.  Conchoidal. 

.5-2 

3.55 

1 

U.  cryst._ 

DLS^OS* 

Lemon-yellow. 

Pearly,    resin- 
ous. 

.  Pinacoidal, 
perfect. 

.5  2 

3.48 

1 

.  foil. 

is203. 

olorless  to 
white. 

Adamantine. 

?.  Uneven. 

.5 

3.70 

1 

sometric. 

As203. 

olorless  to 
white. 

Pearly. 

C.  Pinacoidal, 
perfect. 

2.5 

3.9-4.1 

1 

"abular. 

Sb2S20. 

rownish-red, 
maroon. 

Adamantine. 

C.  Pinacoidal, 
perfect. 

1-1.5 

4.60 

1 

Acicular. 

Sb2O3. 

Colorless    or 
white. 

Adamantine. 

F.  Uneven. 

2  2.5 

5.25 

1.5 

Ig.  96. 

Sb203. 

Colorless   or 
white. 

Pearly,     ada- 
mantine. 

C.  Pmi\c.,per. 
and  prismatic. 

2.5  3 

5.56 

1.5 

iMsmatic 

NH4C1. 

Colorless    or 
•white. 

Vitreous. 

F.  Conchoidal. 

1.5-2 

1.53 

Vol. 

1 

sometric. 
C1.4,p.219 

(NH4)aS04. 

Colorless   or 
white. 

Vitreous. 

F.  Uneven. 

2-2.5 

1.77 

1 

O  rthorh. 

;  — 
HgS. 

Red. 
Vermilion. 

Adamantine. 

C.  Prismatic, 
perfect. 
F.  Uneven. 

2-2.5 

8.10 

Vol. 
1.5 

Class  15, 
p.  219. 

*  —  • 
HgCl. 

Colorless   or 
white. 

Adamantine. 

F.  Conchoida 

1-2 

6.48 

Vol. 
1 

Tetrago- 
nal. 

Ortborh. 

PbCl2. 

Colorless   or 
white. 

Adamantine. 

F.  Uneven. 

1-2 

5.80 

1 

T,  1  ,.     * 

^in^ralscontaini  g  theHakairS^^^                             *  ^^  tor  a  «>™<™  u™     ^ 
,  however,  among  the  fusible  minerals  on  p.  271.                                                                          ^ 

(Page  259.) 
II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

B.— Fusible  from  1-5,  and  Non-volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  I. — Give  a  metallic  globule  when  fused  with  sodium  carbonate  on 

charcoal. 

DIVISION  1.— Silver  Com  pounds. 
DIVISION  2.— Ijcucl  Compounds,  in  part. 


*59 


II.   MINERALS   WITHOUn 
B.— Fusible  from  1—5,  and  Non-volatile. 
PART  I. — Give  a  metallic  globule  when  f  u 

DIVISION  l.-Silver  Compounds.-A  globule  of  silver  is  obtained  by  fusing  on  charcoal 
globule  will  be  brittle. 


General  Characters. 


Contain  sulphur.— Heated  in  the 
open  tube  yield  sulphur  di- 
oxide and  the  oxides  of  either 
arsenic  or  antimony. 

If  the  globule  obtained  by  heat 
ing  on  charcoal  with  NaaCO, 
is  brittle,  it  may  be  converted 
to  pure  silver  by  heating 
O.  F.  with  borax. 
y  Compare  Miargyrite  and 
Polybasite  (p.  250). 


When  heated  in  the  closed  tube  readily  yield  an 
abundant  sublimate  of  sulphide  of  arsenic,  deep 
red,  almost  black  when  hot,  reddish-yellow 
when  cold  (p.  140),  and  beyond  this  a  slight 
sublimate  of  sulphur. 


Contain  chlorine,  bromine,  o 
iodine.— Sublimates  of  thecM0 
ride,  bromide,  or  iodide  of  leaC 
are  obtained  by  heating  will 
galena  in  a  closed  tube  as  di 
reeled  on  p.  68,  §  4. 

The  chloride   and   bromide   ar 
seclile  and  can  be  cut  with 
knife  like  horn. 


Specific  Characters. 


Xanthoconite. 
(Rittingerite.) 


ed 


PUUIllUalO   in    onifrmvu. 

Upon  intense  and  prolonged  heating  in  the  closet 
tube  a  slight  sublimate  of  oxysulphide  of  anti 
mony  deposits  where  the  glass  is  very  hot. 
This  is  black  when  hot,  reddish-brown  when 
cold  (p.  45,  §  3),  and  beyond  it  there  is  a  slight 
deposit  of  sulphur. 


The  sublimate  (lead  chloride)  is  white,  both  when 
hot  and  cold.  


The  sublimate  (lead  bromide)  is  sulphur-yellow 
when  hot,  but  white  when  cold.  The  chlorine 
in  embolite  may  be  detected  as  directed  on  p 
69,  §  5.  


The  sublimate  (lead  iodide)  is  dark  orange-re( 
when  hot,  lemon-yellow  when  cold.  Cupro 
iodargyrite  may  be  identified  by  its  reaction 
for  copper. 


Name  of  Species. 


roustite. 

(Ruby  Silver.) 


'y  rangy  rite. 

(Dark-red  Silver 
Ort 


Pyrostilpnite. 
(Fireblende.) 


Cerargyrite. 

(Horn  Silver.) 


Embolite. 


Bromyrite. 


Miersite. 


lodyrite. 


lodobromite. 


Cuproiodargyrite. 


DIVISION  2  -Lead  Compounds.- Globules  of  lead  and  a  yellow  coating  of  lead  oxide  are 
gives  a  very  similar  reaction,  but  the  globules  of  bismuth  are  brittle.     The  pale  azure-blue  flame  c 
lead  minerals  dilute  nitric  acid  (1  part  HNO3  to  2  of  water)  should  be  used,  and  in  the  solutior 

N.B.-The  various  salts  of  lead  will  be  found  in  this  division,  with  the  exception  of  those  cor 


Carbonates.—  Soluble    in    warm 
dilute    acids    with    evolution 
of    carbon    dioxide    (efferves- 
cence). 
Generally  it  is  best  to  employ 
dilute  HNO8,    but   for  Lead- 
hillite  use  dilute  HC1. 

Heated  in  the  closed  tube  a  sublimate  of  lead 
chloride  is  obtained,  which  fuses  to  colorless 
globules. 

Phosgenite. 

The  dilute  HC1  solution  gives  with  barium  chlo- 
ride a  precipitate  of  barium  sulphate.  Gives  a 
little  water  in  the  closed  tube. 

Leadhillite. 

Gives  water  in  the  closed  tube,  but  does  not  re- 
act for  a  sulphate. 

Hydrocerussite. 

Gives  none  of  the  above  reactions.  In  the  closed 
tube,  usually  decrepitates  and  is  changed  to 
lead  oxide,  which  is  dark  yellow  when  hot. 

CERUSSITE. 

METALLIC   LUSTER.  259 

only  Slowly  or  Partially  Volatile. 

with  sodium  carbonate  on  charcoal. 
h  sodium  carbonate.     When  antimony  is  present,  some  of  it  -will  alloy  with  the  silver  and  the 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

*.gaS.As,S8. 

Ruby-red. 

Adamantine. 

F.  Conchoidal. 

2-2.5 

5.55 

1 

Hex.  Rh. 
Hemimor. 

Mouocl. 
Tabular. 

igaS.As2S,. 

Orange-yellow 
to  clove-brown 

Adamantine. 

C.  Basal. 

2 

5.54 

1 

A.gaS.SbaS3. 

Dark-red    to 
black. 

Adamantine. 

F,  Conchoidal. 

2.5 

5.85 

1 

Hex.  Rh. 
Hemimor. 

Ag3S.SbaS8. 

Hyacinth-red. 

Adamantine. 

C.  Piuacoidal. 

2 

4.3? 

1 

Monocl. 
Tabular. 

«C1. 

Pearl-gray     to 
colorless. 

Adamantine. 

F.    Uneven   or 
hackly. 

2-3 

5.8-6.0: 

1 

Isometric. 

g(Cl,B,). 

Green   or  yel- 
low. 

Adamantine. 

F.  Uneven. 

2-3 

5.80 

1 
1 

Isometric. 

LgBr. 

Green   or   yel- 
low. 

Adamantine. 

F.  Uneven. 

2-3 

5.8-6.0 

Isometric. 

KL 

;u  iso.  w.  Ag. 

Yellow. 

Adamantine. 

2 

1 

Isom.  TeU 

tgl- 

Lemon-yellow 

Resinous. 

C.  Basal. 
F.  Uneven. 

1.5 

5.70 

1 

Hexag. 
Page  190. 

^g(Cl,Br,I). 

Sulphur-yel- 
low to  green. 

Resinous. 

F.    Uneven   or 
hackly. 

2-3 

5.70 

1 

Isometric. 

Vgl.CuL 

Sulphur- 
yellow. 

2 

Massive. 

y  obtained  by  fusion  on  charcoal  with  sodium  carbonate  and  a  little  charcoal  powder.  Bismuth 
•ation,  and  the  conspicuous  iodine  tests  for  lead  (p.  89),  can  be  recommended.  For  the  solution  of 
chloric  and  sulphuric  acids  will  give  precipitates  of  lead  cliloride  and  lead  sulphate,  respectively. 

i 
unds  (mostly  sulphides)  which  have  a  metallic  luster. 


PbCl)2CO»  = 
PbCO3.PbCla. 

Colorless    or 
white. 

Adamantine. 

C.  Basal  and 
prismatic. 

3 

6.2 

1 

Tetrag. 
U.  cryst. 

?ba(Pb.OH)a(C03)a 
SO4  =  2PbC03. 
(Pb.OH)2S04. 

Colorless  or 
white. 

Pearly,    ada- 
mantine. 

C.  Basal,  per. 
F.  Uneven. 

2.5 

6.54 

1.5 

Monocl. 
U.  cryst. 

Pb(Pb.OH)a(CO3)2. 

Colorless   or 
white. 

Pearly. 

1-2 

6.14 

1.5 

Hexag. 
Tabular. 

PbCO3. 

Colorless    or 
white. 

Adamantine. 

F.  Conchoidal. 

3-3.5 

6.55 

1  5 

Orl  h  orb. 
Page  206. 

(Page  260.) 
II.  MINERALS   WITHOUT   METALLIC  LUSTEK. 


B.— Fusible  from  1-5,  and  Non- volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  I. — Give  a  metallic  globule  when  fused  with  sodium  carbonate  on 

charcoal. 

DIVISION  2. — Lead  Compounds,  continued 


260 


II.   MINERALS   WITHOl 

B.— Fusible  from  1—5,  and  Non-volatil 
PART  I.— Give  a  metallic  globule  when 
DIVISION  2.— Lead  Cc 


Cetera!  Characters. 


Sulphates.  —  When  mixed  with 
NuaCC3  and  a  little  charcoal 
powder,  and  fused  in  R.  F.  on 
charcoal,  a  mass  containing 
sodium  sulphide  is  obtained 
which  blackens  a  moistened 
silver  surface  (p.  122,  §  2). 

The  fine  powder  is  rather  soluble 
in  boiling  dilute  HC1.  The  so- 
lution on  cooling  deposits  lead 
chloride,  and,  after  filtering,  it 
gives  with  barium  chloride  a 
precipitate  of  barium  sulphate. 

Phosphates.— A.  few  drops  of  the 
dilute  HNOs  solution,  when 
added  to  ammonium  molyb- 
date,  give  a  yellow  precipitate 
(p.  103,  §  1). 

T  Compare  the  Arsenutes,  be- 
low. 


Give  water  in  the  closed  tube.     The  HC1  solu-" 
tion  gives  a  blue  color  when  ammonia  is  added 
in  excess. 


Specific  Characters. 


Name  of  Species. 


B.  B.  gives  a  strong  soda  flame. 


Gives  much  water  in  the  closed  tube.     Reacts 
for  ferric  iron,  and  a  phosphate  or  arsenate. 
~  Compare  Lossenite,  beyond. 


Arsenates.— A  fragment  of  the 
mineral  when  placed  in  a 
closed  tube  with  a  few  splin 
ters  of  charcoal,  and  heated  in 
tensely  B.  B.,  gives  a  deposit  of 
arsenic  (p.  51,  §  1,  a). 


Vanadates. — Impart  to  the  salt  o 
phosphorus   bead   in    O.  F. 
yellow    to   deep  amber    cole 
which  in  R.  F.  is  changed  t 
green. 


ive  none  of  the  above  reactions. 


usible  B.  B.  alone  on  charcoal  to  a  globule 
which,  on  slow  cooling,  generally  becomes 
distinctly  crystalline.  B.  B.  in  a  closed  tube 
gives  a  slight  sublimate  of  lead  chloride.  


inparts  a  green  color  to  the  salt  of  phosphoru 
bead  in  O.  F.  (chromium^ 


Jives  much  water  in  the  closed  tube. 


he  dilute  HNO3  solution  gives  with  silver  nitrat 
a  precipitate  of  silver  chloride. 
;3f~Compare  Endlichite,  below. 


use  B.  B.  to  a  magnetic  mass.     Lossenite  react 
for  a  sulphate  (p.  122,  §  1). 


The  HNO3  solution  is  rendered  blue  by  ammoni 
(copper} 


mparts  a  bluish-green  color  to  the  NaaCO8  bea 
in  O.  F.  (manganese). 


The  dilute    HNO3   solution    gives    with    silv 

nitrate  a  precipitate  of  silver  chloride. 
Endlichite  is  a  variety  containing  a  little  arsenic 


The  HNO3  solution  is  rendered  blue  by  additio 
of   ammonia   (copper).     Cuprodescloizite 
variety  of  the  following  mineral. 


Gives  water  in  the  closed  tube.     Reacts  for  zinc 


narite. 


ledonite. 


aracolite. 


eudantite. 


NGLESITE. 


anarkite. 


YROMORPHITE. 


auqueliuite. 
(Laxrnaunite.) 


lumbogummite. 


Mimetite. 


Ecdemite. 


Jarminite. 


jossenite. 


Bayldonite. 


Caryinite. 


Vanadinite. 

(Endlichite.) 


Psittacinite. 


Cuprodescloizite. 


Descloizite. 


Gives  water  in  the  closed  tube.     Contains  neither  |Bl.ackebuschite. 
zinc  nor  copper. 


OIVIBION  2.— Lead  Compounds.— Continued  on  next  page. 


METALLIC   LUSTER. 
Dr  only  Slowly  or  Partially  Volatile. 

ed  with  sodium  carbonate  on  charcoal. 
ijbuiids.— Continued. 


260 


Composition. 

i 
Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness.      ( 

Specific 
gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

lonocl. 

>b,Cu)OH]2SO4.    j 

^.zure-blue.      iVitreous.           t 

.  Piuac.,  per. 
\  Conchoidal. 

2.5 

5.45 

1.5     IV 

>b,Cu)OH]2S04?  J 

Bluish-green.    Resinous.           C 

].  Basal,  per. 

2.5-3 

5.40 

1.5     Orthorh. 

>(OH)Cl.Naa804 

Jolorless  or       yitreOus.           'l 
white. 

\  Uneven. 

15 

1.5-2  Orthorh. 

acertani.                 Olive-green,      T 
:"',  Pb,  Cu,  S04,     browu   black.  x 
(P  As)O4. 

lesinous.           ( 

X  Basal. 

3.5-4.5 

4-4.30 

3.5    j! 

lex.  Rh. 

)S04. 

Colorless  or        Afiomantine      ^'  SaSaV    -^  i 
white               AGamauiiuc.     ^  conci!oidal. 

3 

6.35 

2.5     ^ 

)rthorh. 

J.  cry  st. 

Pale-yellow  or  J 

'b2O)bO4.                    white. 

Dearly,               c   Basal  per. 
adamantine 

2-2.5 

6.40 

2      ] 

Monocl. 

b4(PbCl)(P04)3  = 
*Pb3(P04)3.PbCl2. 

Green,   brown, 
yellow,  gray,!] 
white. 

Resinous. 
1 

F.  Uneven. 

3.5-4 

6.5-7.1 

. 
2.     i 

Hexag. 
C1.8,p.2l9 
U.  pris- 
matic. 

>b,Cu)3(PO4)2. 
2(Pb,Cu)CrO4. 

Green  and         j  Resinous.           !F.  Uneven, 
brown.                                                                 

2.5-3 

5.8-6.1 

2? 

Monoel. 

Hexag. 

Globular. 

Hexag. 
C1.8,p.219 
U.  prism. 

Orthorh. 
Orthorh. 

ncertain.                  Yellow,  brown|Gum_like>          p.  Uneven. 
304),  Pb,  Al,  H2C).      and  green.                                        

4-5 

4-4.9 

2? 
1.5 

b4(PbCl)(As04)3= 
Pb3(AsO4)2.PbCl9. 

Colorless,  yel- 
low, orange, 
brown. 

Resinous. 

F.  Uneven. 

3.5 

7-7.2 

'b4As20,.2PbCla? 

Yellow  to 
green. 

Greasy. 

C.  Basal. 

2.5-3 

6.9-7.1 

1.5? 

•b,Fe/",o(AsO«)i»? 

'Carmine-red. 

Vitreous. 

C.  Prismatic. 

2.5 

4.10 

2-3? 

Fe'".OH)9(AsO4)«. 
PbS04.12HaO 

Yellow  to 
brownish-red. 

Resinous. 

F.  Uneven. 

3-4 

2-2.5 

Orthorh. 
Mam  mill. 

1Pb,Cu)3(AsO4)2.       Grass-  to  black- 
Pb,Ou)(OH)a.H9O.|     ish-irieen. 

Resinous. 

F.  Uneven. 

4.5 

5.35 

2  3? 

l«AsaOg.                   Brown. 

..    _    JI,,      pa      ]\lgr  £   Pb. 

I  Resinous. 

C.  Pinacoidul. 
F.  Uneven. 

3-3.5 

4.30 

2.5 

Massive. 

i  Hexag. 
Page  190. 
U.  prism. 
Mammill. 
earthy. 

>b4(PbCl)(V04)3  =  Huhy-i-ed, 
3Pb,(V04)a.PbCla.!     b»-own  an(i 
t5!  is-,  w  v                      yellow. 

1  Resinous. 

?.  Uneven. 

3 

6.9-7.1 

1.5 

2? 

IBrowu  to 
i}(ROH)V04.               greenish- 
U-Pb,  Zn&Cu.                          black 

Resinous, 
greasy 

F.  Uneven. 

3.5 

6.20 

1.5 

Orthor. 
Radiated. 

Orthorh, 
U.  cry  st. 

<  Monocl. 

!Pb(Pb.OH)V04. 

;?in  iso.  \v.  Pb. 

IBrowuish- 
black,  browi 
and  red. 

Resinous, 
greasy 

F.  Uneven. 

3.5 

6-6.10 

1.5 

Uncertain. 
TO4),  Pb,  Fe,  M 
HaO. 

u,  Dark  brown. 

i 

1.5 

(Page  261.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

B. — Fusible  from  1-5,  and  Non-volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  I.— Give  a  metallic  globule  when  fused  with  sodium  carbonate  on 

charcoal. 

DIVISION  2.— Lead  Compounds,  continued. 


261 


II.   MINERALS   WITHO 

B.—  Fusible  from  1—5,  and  Non-volati 

PART  I.— Give  a  metallic  globule  whei 

DIVISION  2.— Lead  C 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

Chronialea.—  Impart  to  the  salt  of 

Streak  orange-yellow. 

rocoite. 

phosphorus  bead   in   O.   F.    a 
green  color. 

Streak  brick-red. 

hoenicochroite. 

Molybdate.—  Gives    the  test    for 
molybdenum  when  treated  as 
directed  on  p.  96,  §  4. 

With  salt  of  phosphorus  the  bead  in  R.  F.  is  green, 
but  in  O.  F.  it  is  yellowish-green  when  hot, 
almost  colorless  when  cold. 

Wulfenite. 

Tungstate.—  Decomposed  by  boil- 
ing with  HC1,  leaving  a  yellow 
residue  of  lungstic  oxide. 

[f  the  tungstic  oxide  (after  decanting  off  the  HC1 
is  treated  first  with  ammonia,  then  with  HC1 

tolzite. 

in  excess,  and  boiled  with  tin,  a  fine  blue  color 
is  obtained  (p.  128,  §  1). 

aspite. 

Contain     antimony.—  Aloue     on 
charcoal  in  R.  F.  give  a  malle- 
able lead  globule  and  coatings 
of    both    lead    and   antimony 
oxides.       Mixed     with    three 
volumes  of  Na2CO3  and  fused 
in  charcoal  in  R.  F.,  give  a 
somewhat  brittle  globule  (alloy 
of  lead   and  antimony)  which 
yields  a  sublimate  of  oxide  of 
antimony   when    roasted   in   a 
bent  open  tube  (Fig.  17,  p.  19). 

In  the  closed  tube  give    a  sublimate    of  lead 
chloride,  which  fuses  to  colorless  globules. 

adorite. 

chrolite. 

In  the  closed  tube  gives  water. 

3indheimite. 

Contain  chlorine,  but  do  not  give 
the  reactions  of  the  foregoing 
sections.—  Soluble     in     warm 
dilute    HNO3.      The    solutioc 
gives  with  silver  nitrate  a  pre 
cipitate  of  silver  chloride. 

B.  B.  give  a  blue  or  green  flame. 
The  HNO3  solution  is  rendered  blue  by  additio 
of  ammonia  (copper}. 

Percylite. 
(Boleite.) 

Cumengite. 

Give  no  water  in   the  closed  tube,  but  yield 
sublimate  of  lead  chloride  which  fuses  to  colo 
less    globules.     Cotunnite    is  wholly   volati 
when   heated   in   the  closed   tube,    while    tl 
others  leave  a  residue  of  easily  fusible  lea 
oxide. 

Cotuimite. 

Penfleldite. 

Matlockite. 

Mendipite. 

Gives  sublimates  of  both  water  and  lead  chloric 
in  the  closed  tube. 

Laurionite. 

Contains     iodine,  —  The    dilut< 
HNO3  solution  gives  with  silve 
nitrate  a  precipitate  of  silve 
iodide 

3  Gives  a  sublimate  of  lead  iodide  (dark-red  whe 
hot,  yellow  when  cold)  and  iodine  vapors  inth 
r     closed  tube. 

Schwartzenbergit 

DIVISION  2.— L,eart  Compounds.— Concluded  on  next  page. 


[?'   METALLIC   LUSTER, 
e  or  only  Slowly  or  Partially  Volatile. 
Jsed  with  sodium  carbonate  on  charcoal. 
>  I  pounds. — Continued. 


261 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
uess. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

bCrO4. 

Bright-red. 

Adamantine. 

?.  Uneven. 

2.5-3 

5.9-6.1 

1.5 

Monocl. 
U.  cryst. 

!.3bCr04.PbO. 

Red. 

Resinous. 

3.  Piuacoidal, 
perfect. 

3-3.5 

5.75? 

1.5 

Orthorh. 
U.  mass. 

bMo04. 

Yellow, 
orange,  red, 
gray,  white. 

Vitreous  to 
adamantine. 

F.  Uneven. 

4.5-5 

6.05 

2 

Tetrag. 

Cl.  23,  p.  219. 

U.  tabular 

bWO4. 

Light  green, 
yellow,  brown 
or  red. 

Resinous. 

P.  Uneven. 

3 

7.9-8.1 

2.5-3 

Tetrag. 
Cl.20,p.219. 

'bW04. 

Wax-brown. 

Resinous. 

C.  Piuacoidal, 
perfect. 

2.5-3 

2.5-3 

Monocl. 

'bClSb02. 

Smoky-  to 
yellowish- 
brown. 

Resinous. 

C.  Piuacoidal, 
perfect. 

3.5-4 

7.0 

1.5 

Orthorh. 

>b4SbaO7.PbCla? 

Sulphur-  to 
grayish-yellow 

Adamantine. 

1.0? 

Orthorh. 

Ju  certain. 
5b2O6,  PbO  and 
H20. 

Gray,  yellow, 
brown. 

Resinous  to 
dull. 

F.  Uneven. 

4 

4.6-5.0 

3-4 

Amorph. 

3bCuCl2(OH)a. 

Indigo-blue. 

Brilliant. 

C.  Cubic,  per. 

3 

5.08 

1 

Isometric. 
Cubic. 

PbCuCl2(OH)2. 

Indigo-blue. 

Brilliant. 

C.  Pyramidal. 

3 

4.71 

1 

Tetrag. 

PbCl2. 

Colorless  or 
white. 

Adamantine. 

F.  Uneven. 

1-2 

5.80 

1 

Orthorh. 

2PbCl2.PbO. 

Colorless  to 
wbite. 

Vitreous  to 
greasy. 

D.  Basal,  per. 
F.  Uneven. 

2.5 

1 

Hexag. 
Prismatic. 

PbCl2.PbO. 

Pale  yellow  to 
white. 

Adamantine, 
pearly. 

C.  Basal. 
F.  Uneven. 

2.5-3 

7.20 

1 

Tetrag. 
Tabular. 

Pb012.2PbO. 

Pale  yellow  to 
white. 

Pearly  to 
adamantine. 

C.  Prismatic, 
per.  and  basal. 

2.5-3 

7.10 

1 

Orthorh. 
Columnar 

PbCl(OH). 

Colorless  or 
white. 

Adamantine. 

F.  Uneven. 

3-3.5 

1 

Orthorh. 

Pb(I,Cl)2.2PbO. 

Honey-  to 

straw-yellow. 

Adamantine. 

2-2.5 

6.2-6.3 

1 

Hex.  Rh. 

(Page  262.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTEK. 

B.— Fusible  from  1-5,  and  Non-volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  I. — Give  a  metallic  globule  when  fused  with  sodium  carbonate  on 

charcoal. 

DIVISION  2 — Lead  Compounds,  concluded. 
DIVISION  3. — Bismuth  Compounds. 


262 


II.   MINERALS  WITHOI 

B.— Fusible  from  1—5,  and  Non-volati 

PART  I. — Give  a  metallic  globule  when 

DIVISION  2.— Lead  C< 


General  Characters. 


Silicates.— The  three  first  mm- 
ertils  are  readily  decomposed  *£ 
by  HNO3  aud  yield  gelatinous 
silica  upon  evaporation.  Mela- 
notekite  and  Kentrolite  are 
best  decomposed  by  HC1,  but 
contain  too  little  silica  to  give 
a  good  jelly.  They  leave  a 
residue  of  silica,  however,  when 
the  HC1  solution  is  evaporatec 
to  dryuess  and  then  treatec 
with  acid.  Hyalotekite  is 
insoluble  in  acids,  but  may^bt 
tested  as  directed  on  p.  110,  §4 


Oxides.—  Do  not  give  the  reac 
tions  of  the  foregoing  minerals 


Specific  Characters. 


Name  of  Species. 


Jives  the  reaction  for  sulphur  (p.  122,  §  2). 

"be  only  mineral  containing  the  sulphite  radical.  _ 


Distinguished  by  differences  in  physical  proper 
ties  and  by  the  presence  of  calcium  (CaO  =  9$ 
in  Ganonmlite. 


Barysilite. 


B.  B.  in  R.  F.  fuses  to  a  magnetic  bead, 


Imparts  a  red  dish-  violet  color  to  the  borax  bead 

in  O.  F.  (manganese).     Soluble  in  HC1  with  Kentrolite. 
evolution  of  chlorine. 

and  borou 


.  §  3> 


The  colors  of  the  different  minerals  are  very 
characteristic.  Phutnerite  and  Minium  give 
oxygen  gas  when  heated  in  the  closed  tube 
(p  100  §1)  and  leave  readily  fusible  lead 
oxide  (PbO). 


Qanoinalite. 


Melanotekite. 


Hyalotekite. 


Plattnerite. 


Minium. 


Massicot. 


DIVISION  3  -Bismuth  Compounds.— ffto&tdw  of  bismuth  which  are  brittle  and  a  yellou 
red  sublimate  obtained  by  heating  on  charcoal  with  a  mixture  of  potassium  iodide  and  sulphur  (p. 


Carbonates.  —  Dissolve  in  HC1 
with  evolution  of  carbon  di- 
oxide (effervescence). 


Contains  chlorine.  —  The  dilute 
HNOs  solution  gives  with  silver 
nitrate  a  precipitate  of  silver 
chloride. 


In  the  closed  tube  gives  water. 


Silicates.— Soluble  in  HC1,  and 
yield  gelatinous  silica  upon 
evaporation. 


Vanadate. — Imparts  to   the  sal 
of  phosphorus  bead  in  O.  F.  a 
and  in  R.  F.  a  green 


yellow 
color. 


Arsenates. — A  fragment  of  thi 
mineral  when  placed  in  i 
closed  tube  with  a  few  splin 
ters  of  charcoal,  and  heate< 
intensely  B.  B.,  gives  a  deposit 
of  arsenic  (p.  51,  §  1,  a). 

Mixite  (p.  264). 


n  the  closed  tube  gives  little  or  no  water. 


Bismutosphserite. 


n  the  closed  tube  gives  water. 


Jismutite. 


Distinguished  by  differences  in  crystallization. 


Soluble  in  HC1. 


Imparts  to  the  salt  of  phosphorus  bead  in  R. 
a  green  color  (uranium). 


Daubreeite. 


Eulytite.  ' 


Agricolite. 


Pucherite. 


Walpurgite. 


Atelestite. 


React    only    for   arsenic, 
Atelesite  decrepitates. 


bismuth    and    water. 


^Jjff     V^uiupaic    JUtMtiiG  \\J.    ~ut/. 

Tellurate.— When  mixed  with  Na,CO,  and  charcoal  powder  and  heated  in  a  closed 
tube,  sodium  telluride  is  formed,  which,  when  treated  with  water,  yields  a 
reddiflh-violet  solution  (p.  124). . 


Montanite. 


METALLIC   LUSTER, 
or  only  Slowly  or  Partially  Volatile. 

;ed  with  sodium  carbonate  on  charcoal, 
pounds.— Concluded. 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

H2CaSiO4. 
2(PbOCa)SO,. 

White. 

Dull-white. 

2.5-3 

3.43 

3 

Granulaiv 

Hexag. 
Lamellar. 

b3SiaO7. 

White. 

Pearly. 

C.  Basal. 

3 

6.50 

2.5 

b3Si2O7.(Ca,Mn)2 
Si04. 

Colorless  to 
Cray. 

Resinous  to 
vitreous. 

F.  Uneven. 

3 

5.74 

3? 

Tetrag. 

BV"4O3)Pb3(Si04)3 

Dark-brown  to 
black. 

Sub-metallic. 

F.  Uneven. 

5-5.5 

5.85 

2-2.5 

Orlhorh. 

VIn4Os)Pb3(SiO4)s. 
e  iso.  w.  Mn. 

Black. 

Sub-metallic. 

F.  Uneven. 

5-5.5 

6.19 

2-2.5 

Orthorh. 

Massive. 

14(F,OH)B(SK)3)6. 

,  =  Ph.  Ba  &  Ca. 

White  to  gray. 

Vitreous  to 
greasy. 

C.  Two  direc- 
tions. 

5-5.5 

3.80 

3? 

*bO2. 

Brown-black. 

Sub-metallic. 

F.  Uneven. 

5-5.5 

8.50 

1.5 

Tetrag. 
U.  mass. 

'b304. 

Red. 

Dull  or  greasy. 

2-3 

4.6? 

1.5 

Pulveru- 
lent, 

•bO. 

Sulphur-  to  red- 
dish-yellow. 

Dull. 

2 

8-9.2 

1.5 

Massive. 
Scaly. 

ing  of  bismuth  oxide  are  easily  obtained  by  fusion  B.  B.  on  charcoal  with  sodium  carbonate.     The- 
§  2)  may  be  recommended  as  a  very  characteristic  test  for  bismuth. 


3iO)2CO3. 

White  or  gray. 

Dull. 

F.  Uneven. 

3-3.5 

7.42 

1.5 

Botryoid. 

M.-tssive. 

Am  or  ph. 
Earthy. 

3iO)(Bi.2OH)CO3. 

White,  green, 
yellow. 

Dull. 

4-4.5 

6.9-7.7 

1.5 

Bi203.BiCl3.3H2O. 

Yellowish-  to 
grayish-white. 

Dull. 

2-2.5 

6.45 

1.5? 

Am  or  ph. 
Earthy. 

Tsom.  Tet. 
U.  cryst. 

5i4(SiO4)3. 

Hair-brown, 
yellow, 
colorless. 

Resinous  to 
adamantine. 

F.  Uneven. 

4.5 

6.1 

2 

5i4(Si04)3. 

Yellow,  hair- 
brown. 

Adamantine. 

3? 

6? 

2 

Monocl. 
Globular. 

3iV04. 

Reddish  - 
brown. 

Vitreous  to 
adamantine. 

C.  Basal,  per. 
F.  Uneven. 

4 

6.25 

2 

Orthorh. 
U.  cryst. 

5i10(U02)3(OH)24 
(As04)4. 

Wax-yellow. 

Adamantine  to 
greasy. 

C.  Pinacoidal. 

3.5 

5.76 

1.5 

Tricliuic. 

Bi.2OH)(BiO)2 
AsO4 

Sulphur- 
yellow. 

Adamantine. 

F.  Uneven. 

3-4 

6.40 

1.5 

Monocl. 

:Bi(OII)3.2BiAs04? 

Yellowish- 
green  to  wax- 
yellow. 

Resinous  to 
adamantine. 

F.  Uneven. 

5 

6.80 

1.5? 

Mamruill. 

Bi.20H)2TeO4. 

Yellow,  green 
and  white. 

Dull. 

1.5? 

Massive. 
Earthy. 

(Page  263.) 


II.  MINERALS  WITHOUT   METALLIC   LUSTER. 


B.— Fusible  from  1-5,  and  Won- volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  I. — Give  a  metallic  globule  when  fused  with  sodium  carbonate  on 

charcoal. 

DIVISION  4.— Antimony  Compounds. 
DIVISION  5. — Copper  Compounds,  in  part. 


II.  MINERALS   WITHOI 
B.-Fusible  from  1-5,  and  Non-volatil 
PAET  I.— Give  a  metallic  globule  when 
4.-Antimony  Compounds.-^^  of  antimony  which 


General  Characters. 

F^d^iUr^CoTu^n  treated 
with  HC1  and  boiled  with  tin, 
the  solution  assumes  a  violet 
color  (titanium,  p.  127.  fe  *). 


Specific  Characters. 

_ 

ww  gives  a  reaction  for  lead. 
Compare  DerbyUte  (p.  »RM. 


Mauzeliite, 


Lewisite. 


B.  B.  fuses  to  a  magnetic  mass. 


Gives  no  reaction  for  titanium 


B.  B.  fuses  to  a  dark  non-magnetic  sla 


K.B.-H-*  a,l  of  the  .iuevals  containing  copper  wU 


reaction  tor 


Carbonates.  —  Soluble  in  HC1 
with  evolution  of  carbon  di- 
oxide (effervescence). 


Give  water  in  the  closed  tube.     Readily  distin 
guished  by  their  color. 


Contain  chlorine.—  Impart  to  th 
blowpipe  flame  an  azure-blu 
color  without  previous  moist 
ening  with  HC1.  Silver  nitrat 
gives  a  precipitate  of  silve 
chloride  when  added  to  th 
dilute  UNO 3  solution. 


Contains    iodine.  —  Colors    th 
blowpipe  flame  intense  green 


UPRITE. 

(Ruby  Copper.) 


MALACHITE. 


AZURITE. 


_ 

The  HC1  solution  gives  a  slight  precipitate  with 

barium  chloride  (sulphate). 
Spangolite  exhibits  pyro-electricity  (p. 


Spangolite. 


Give  acid  water  in  the  closed  tube. 


Heated  with  potassium  bisulphate  in  a  close 
tube  gives  vapors  of  iodine. 


Connellite. 


Nantokite. 


Atacamiie. 


Footeite. 


Marshite. 


5.-Copper  Compounds.— Continued  on  next  page. 


METALLIC   LUSTER, 
or  only  Slowly  or  Partially  Volatile. 

ed  with  sodium  carbonate  on  charcoal. 
COaUn9  of  anUinony  o*i«e,  are  obtained  by  fusing  B.  B.  on  charcoal  with  sodium  carbonate. 


263 


Composition. 

—  

Color. 

—  ' 
Luster. 

•  '  : 

Cleavage  and 
Fracture. 

•  i    i 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

a,Pb,Na2)4 
TiRbxOiA 

Brown. 

6-6.5 

5.10 

Isometric. 

a,Fe)6Ti,Sbc024. 

Honey-yellow 
to  brown. 

Resinous. 

C.  Octahedral. 

5.5 

4.95 

3-4? 

Isometric. 

i"sSb9O7. 

Greenish- 
yellow. 

Resinous. 

5.82 

4-5? 

? 

iSbaO«. 

Honey-yellow. 

F.  Uneven. 

_  —  '  ~ 

5.5 

—      • 

4.70 

—  — 

Tetrag. 



of 


a  this  division.     Most  of  them  have  either  a  green  or  a  blue  color. 


,  •  — 

)uaO. 

.  

Intense  ruby- 
red. 


Adamantine. 

~ 

F.  Conchoidat 
or  uneven. 

3.5-4 

6.00 

3 

sometric. 
1.4,p.219 
igs.  95 
to  104. 

Cu.OH)2CO3  = 

Bright-green. 

Vitreous. 

C.  Basal,  per. 
?.  Uneven. 

3.5-4 

3.9-4.0 

3 
3 

U.mamm. 
[onocli 

Cu.OH)2Cu(CO3)2 
4)CuCO3  Cu(OH)a 

Intense  azure- 
blue. 

Vitreous. 

F.  Conchoidal 
or  uneven. 

3.5-4 

3.77 

U.  cryst. 
lexag. 

A1C1)SO4. 

Dark-green. 

Vitreous. 

C.  Basal,  per. 

2-3 

3.14 

3 



15H2O 

Beautiful-blue 

Vitreous. 

F.  Uneven. 

o 

3.36 

2.5 
1.5 
3-4 

Msmatic 

CuCl. 

Colorless  or 
white. 

Adamantine. 

F.  Conchoidal 

2-2.5 

3.93 

Isometric. 
Orthorh. 

Cu2Cl(OH)3  = 

Deep  emerald- 
jjreen. 

Adamantine, 

vitreous. 

C.  Pinac.,  per 
F.  Conchoidal 

3-3.5 

3.75 

U.  cryst. 

8Cu(OH)2.CuCU. 
4H2O 

Deep-blue. 

1.5? 

Monocl. 

iCuI. 

Reddish- 
brown 

Resinous. 

—  • 

F.  Uneven. 

.  —  

.  

Isom.  Tet. 

— 

(Page  264.) 

II.  MINERALS    WITHOUT   METALLIC   LUSTER. 

B.— Fusible  from  1-5,  and  Non-volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  I. — Give  a  metallic  globule  when  fused  with  sodium  carbonate  on 

charcoal. 

DIVISION  5. — Copper  Compounds,  continued. 


II.   MINERALS   WITIK 


B.— Fusible  from  1—5,  and  Non-vola 

PAKT  I. — Give  a  metallic  globule  wher 

DIVISION  5. — Coppe 


Wholly  sol- 
uble in  wa- 
ter. 

Gives  much  water  in  the  closed  tube.  Character- 
ized by  its  color. 

O^ialcanthite. 
(Blue  Vitriol.) 

Gives  little  or  no  water  in  the  closed  tube. 

Hydrocyanite. 

Yields  a  magnetic  mass  after  heating  B.  B.  on 
charcoal. 

Pisanite. 

Sulphates.  —  The  di- 
lute HC1  solution 
gives  with  barium 
chloride  a  precip- 
itate   of    barium 
sulphate.        Give 
the  sulphur  reac- 
tiou  on  moistened 
silver  after  previ- 
ous   fusion  with 
Na  2  CO  3  and  char- 
coal powder   (p. 
122,  §  2). 

Imparts  a  yellow  color  to  the  blowpipe  flame 
(sodium). 

Krohnkite. 

Reacts  for  potassium  (p.  106,  §  3). 

Cyanochroite. 

Insoluble  or 
only  partly 
soluble  in 
water. 

Gives  little  or  no  water  in  the  closed  tube. 

Dolerophanite. 

The  HC1  solution  gives  with  ammonia  a  precipi- 
tate of  aluminium  hydroxide  (seen  with  diffi- 
culty unless  filtered). 

Cyanotrichite. 
(Lettsomite.) 

Gives  the  reaction  for  an  arsenate  (p.  51,  §  c). 

Lindackerite. 

Distinguished  by  differences    in  crystallization 
and  color. 
Herrengrundite  reacts  for  calcium. 

Brochantite. 

Langite. 

Herrengrundite. 

Nitrate.—  Heated    in  the  closed 
tube  gives  red  vapors  of  nitro- 
gen dioxide,  NOa. 

Gives  strongly  acid  water  in  the  closed  tube. 

Gerhard  tite. 

Arsenates.  —  When    heated    in- 
tensely B.  B.  in  a  closed  tube 
with  a  few  splinters  of  char- 
coal,  most  of    these  minerals 
(all  of  the  easily  fusible  ones) 
are  reduced  and  an  arsenical 
mirror  is  formed  (p.  51,  §  a). 
When  the  foregoing  treatment 
does  not  yield  a  satisfactory 
result,   the  method  given  on 
p.  51,  §  c,  may  be  used. 

5^*"  Arsenates  concluded  on  next 
page. 

Fuses  B.  B.  on  charcoal  to  a  magnetic  mass. 
Reacts  for  ferric  iron  (p.  85,  §4). 

Chenevixite. 

A  drop  of  dilute  H2SO4  produces  in  the  concen- 
trated HC1  solution  a  precipitate  of    calcium 
sulphate  (p.  59,  §  3). 

Conichalcite. 

Tyrolite. 

Gives  a  coating  of  oxide  of  zinc  when  fused  on 
charcoal  in  R.  F.  with  a  little  Na2CO3. 

Veszelyite. 

Heated  on  charcoal  with  potassium  iodide  and 
sulphur  gives  a  red  sublimate  (p.  55,  §2). 

Mixite. 

Imparts  to  the  salt  of  phosphorus  bead  in  R.  F. 
a  green  color  (uranium). 

Zeunerite. 

Barium  chloride  produces  in  the  dilute  HC1  solu- 
tion a  precipitate  of  barium  sulphate. 

Lindackerite. 

B.  B.  cracks  and  then  fuses.     Reacts  for  alumin- 
ium (p.  42,  §  2). 

Liroconite. 

Has  a  tendency  to  exfoliate  and  fall  to  pieces 
when  heated  B.  B. 

Clinoclasiie. 

QIVISIOI?  5  —  CoDDer  Compounds.  —  Concluded  on  next  page. 

METALLIC   LUSTER. 


264 


ilj  or  only  Slowly  or  Partially  Volatile, 

lied  with  sodium  carbonate  on  charcoal. 
Compounds. — Continued. 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
nation. 

jS04.5H20.    ' 

Azure-blue 
(rather  deep). 

Vitreous. 

F.  Conchoidal. 

2.5 

2.2 

3 

Tricliuicr 
Page  217. 

uSO4. 

Pale  green, 
brownish- 
yellow. 

3 

Orthorh. 

re,Cu)SO4.7HaO. 

Bright-blue. 

Vitreous. 

C.  Basal. 

2.5 

3-4 

Monocl. 

uSO4.Na2SO4. 
2H2O. 

Azure-blue. 

Vitreous. 

0.  Prismatic. 
F.  Conchoidal. 

2.5 

1.98 

1 

Monocl. 

uS04.K2S04. 
6H2O. 

Blue. 

Vitreous. 

1? 

Monocl. 

:uao)so4. 

Brown. 

3 

Mouocl. 

!u4Al2S010.8H2O. 

Clear-blue. 

Pearly. 

2.7 

3 

Orthorh. 
U.  capilL 

3u.OH)4Cu2Ni3 
304)(As04)4.5H2O. 

Verdigris-  to 
apple-green. 

Vitreous. 

2-2.5 

2-2.5 

2-3? 

Orthorh. 

:uS04.3Cn(OH)2. 

Deep  emerald- 
green. 

Vitreous. 

C.  Pinac.,  per. 
F.  Uneven. 

3.5-4 

3.9 

3.5 

Orthorh. 
U.  cryst. 

;uSO4.3Cu(OH)2. 
H20. 

Blue  to  green- 
ish-blue. 

Vitreous. 

C.  Pinacoidal. 

2.5-3 

3.50 

3.5 

Orthorh. 

!(Cu.OH)2SO4. 
Cu(OH)2.3H2O. 

?a  iso.  \v.  Cu. 

Emerald- 
green. 

Vitreous. 

C.  Basal,  per. 

2.5 

3.1 

3.5 

Monocl, 

:u(NO3)a. 
3Cu(OH)2 

Deep  emerald- 
green. 

Vitreous. 

C.  Basal,  per. 

2 

3.42 

3 

Orthorh. 

Dua(FeO)2 
(As04)2.3H20. 

Dark-green  to 
olive-  green. 

Dull. 

F.  Uneven. 

3.5-4.5 

3.93 

2.5 

Massive. 
Compact 

Cu,Ca)(Cu.OH) 
(As,P)O44H2O. 

Emerald-green 

Vitreous. 

F.  Splintery. 

4.5 

4.12 

2.5-3 

Massive. 
Mam  mill. 

,Cu,ca)(Cu.OH)4 
(AsO4)2.7H2O. 

Pale  apple- 
green. 

Pearly  and 
vitreous. 

C.  Basal,  per., 
foliated. 

1-1.5 

3.05 

2-2.5 

Orthorh. 

7(Cu,Zn)O. 
(As,P)2O5.9H2O? 

Greenish-blue. 

Vitreous  ? 

3.5-4 

3.53 

Triclinic? 

Dua(Cu.OH)8 
Bi(AsO4)5.7H2O? 

Pale-green. 

Vitreous. 

3-4 

3.79 

2 

Capillary. 

Cu(U02)2(As04)2. 
8H2O. 

Emerald- 
green. 

Pearly  and 
vitreous. 

C.  Basal,  per. 
F.  Uneven. 

2-2.5 

3.2 

3 

TetniF 
U.  tabul. 

Cu.OH)4Cu2Ni3 
(SO4)(AsO4)4.5H2O 

Verdigris-  to 
apple-green. 

Vitreous. 

2-2.5 

2-2.5 

2-3? 

Orthorh. 

Cu.OH)9 
[A14(OH)«1 
(AsO4)5.20H2O? 

Sky-blue,  at 
times  greenish. 

Vitreous. 

F.  Uneven. 

2-2,5 

2.9 

3-3.5 

Monocl. 

Cu.OH),As04. 

Dark-green  or 
bluish-green. 

Pearly  and 
vitreous. 

C.  Basal,  per. 

2.5-3 

4.36 

2-2.5 

Monocl. 

(Page  265.) 
II.  MINERALS   WITHOUT   METALLIC   LUSTER. 


B.    fusible  from  1-5,  and  Non- volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  I. — Give  a  metallic  globule  when  fused  with  sodium  carbonate  on 

charcoal. 

DIVISION  5. — Copper  Compounds,  concluded. 


II.   MINERALS   WITHOUT 

B.— Fusible  from  1—5,  and  Non-volatile, 
pABT  i, — Give  a  metallic  globule  when  fui 
DIVISION  5.— Copper  C 


General  Characters. 


Specific  Characters. 


Arsenates,    concluded.  -  When  After  Jf using  B    B, 
heated   intensely  B.   B.   in  a 


Decrepitates  violently  when  heated  in  tiie  closed 


tube. 


Name  of  Species. 


Chalcophyllite. 


in  the  forceps  the  globule 
crystalline.     Euchroite  con- 
""*    IL 


ivenite. 


heated  intensely  B  B.  in  a  ^™^ '  of 'crystoUtoion,  and  loses  i 
closed  tube  with  a  few  »l£  £«»  ™**  °ose/tube  ,!ke  gypsum  (p  82 
tprs  of  charcoal,  most  of  these  "auiij  .  water  at  a  fain 


ters  of  charcoal,  most  of  these 
minerals  (all  of  the  easily  fusi- 
ble ones)  are  reduced  and  an 
arsenical  mirror  is  formed  (p. 
51  §  a).  When  the  foregoing 
treatment  does  not  yield  a  satis- 
factory result,  the  method 
"  51,  §<?,  may  be 


given 
used. 


on  p. 


As  these  minerals  have  not  been  observed  in  dis- 
tinct crystals,  a  quantitative  determination  ol 
some  of  their  constituents  may  be  necessary  lor 
identification.  Erinite  contains  5  percent  o 
water,  Cornwallite  8,  Leucochalcite  10,  and 
Trichalcite  16. 


Phosphates.-A.  little  of  the  HNO 
solution  when  added  to  ammo 
nium  raolybdate  gives  a  yellow 
precipitate  (p.  102,  §  1). 


§  1,  b).    Oliviuite  gives  a  little  water  at  a 
red  heat. 


faint  Euchroite. 


riuite. 


Cornwallite. 


eucochalcite. 


Trichalcite. 


Fuses  B.  B.  on  charcoal  to  a  magnetic  mass 
Reacts  for  ferric  iron  (p.  85,  §4). 


Imparts  to  the  salt  of  phosphorus  bead  in  R. 
a  ffreen  color  (uranium). 


Distinguished  by  differences   in    crystallizatio 
and  physical  properties. 


Vanadates  -Give  the  reaction  for  vanadium  when  treated  as  directed  on  p.  13 


2 


tes  -ve     e  reacon    o 

Calciovolborthite  contains  5  and  Volborthite  34  per  cent  of  water. 


i._ Decomposed  by   boiling  HC1,  leaving  a  yellow  residue  of 


Chalcosiderite. 


Torbernite. 

(Uran-mica.) 


Libethenite. 


Dihydrite. 


Pseudomalachite. 


Calciovolborthite. 


Volborthite. 


Cuprotungstite. 


the  volatile  subli 


for  th 


'd  tube  a  little  water  aud  a  less  volatile,  liquid  i 
obtained.     Break  off  the  end  of  the  tube  and  testjchalcomenite. 
flame  coloration  as  directed  on  p.  107. _^ 


ETALLIC   LUSTER. 

only  Slowly  or  Partially  Volatile. 

with  sodium  carbonate  on  charcoal. 
poimds. — Concluded. 


265 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness.      ( 

Specific 
Sravity. 

Fusi- 
ility. 

I 

Crystalli- 
zation. 

T     v     T>y, 

u.OH)3AsO4. 
Cu(OH)2.3£H2O. 

rass-green. 

early  and        ^ 
vitreous. 

3.  Basal,  per. 

2.4-2.6 

2-2.5  \ 

lex.  rvn. 

J.  tabul. 

i(Cu.OH)AsO4. 

lackish-    and 
olive  -  green 
to  brown. 

itreous  to       i-j 
adamantine. 

Uneven. 

.4 

2-2.5  - 

Drthorh. 
J.  prism. 

i(Cu.OH)AsO4. 
3H2O. 

merald-green 

itreous. 

.  Uneven. 

3.5-4 

.39 

2-2.5 

Drthorh, 

i(Cu.OH)4(As04)2 

merald-green 

Dull  to  resin- 
ous. 

.  Uneven. 

4.5-5 

.04 

2-2.5 

[ammilL 

u(Cu.OH)4 
(AsO4)2.3H2O. 

Emerald-green 

.  Uneven. 

4.5 

4.16 

2-2.5 

Massive. 

u(Cu.OH)As04. 
V                   H20 

White  to  pale- 
green. 

ilky. 

2-2.5 

Capillary. 

us(As04)a.5H20. 

Verdigris- 
green. 

Silky. 

2.5 

2-2.5 

ladiated. 

'u(Fe,Al)aFeO)4 
(P04)4.8H2O. 

Light-  to  dark 
green. 

Vitreous. 

C.  Piuac.,  per. 

4.5 

3.1 

4-4.5 

Triclinic. 

!u(U02)2(P04)2. 
8H2C 

Smerald-  to 
apple-green 

Pearly  and 
vitreous. 

C.  Basal,  per. 
foliated. 

2-2.5 

3.4-3.6 

3 

T.  etrag. 
U.  tabul. 

)u(Cu.OH)PO4. 

Dark-green  to 
olive-green 

Resinous. 

F.  Uneven. 

4 

3.6-3.8 

2-2.5 

Orthorh. 

)u(Cu.OH)4(PO4)2 

Dark  emerald 
green. 

Vitreous. 

T.  Uneven. 

4.5-5 

4-4.4 

2-2.5 

Tricliuic  ? 

Cu.OH)3P04. 

Emerald-  to 
dark-green 

Vitreous. 

?.  Uneven. 

4.5-5 

4.1-4.4 

2-2.5 

U.  botryo. 

XCu.OH)PO4. 
H20 

Emerald-gree 

Vitreous. 

F.  Uneven. 

3-4 

4.07 

2-2.5 

U.  fibrous. 

'Pftlmlfir 

Cu,Ca)(Cu.OH) 

Green  to  gray 

3.  Pinacoida 

3.5 

3.5- 
3.8 

1.5-2 

Granular. 

R.OH)3VO4.6H20 

^  —  Cu   Ca  Mg  &  Ba 

C.  Pinac.,  pe 

3-3.5 

3.55 

1.5? 

Tabular. 

3uWO4. 

''a  iso  w  Cu. 

Pistachio-  to 
olive-green. 

Vitreous. 

C.  Pinacoidal. 

4.5-5 

3? 

Granular. 

CuSeO3.2H2O. 

Beautiful-blu< 

3  Vitreous. 

F.  Uneven. 

2.5-3 

3.76 

1.5 

MonocL 

(Page  266.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

B.— Fusible  from  1-5,  and  Non-volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  II. — Become  magnetic  after  heating  before  the  blowpipe  in  the 

reducing  flame. 

DIVISION  1. — Soluble  iu  hydrochloric  or  nitric  acid  without  a  perceptible  residue  and 
without  yielding  gelatinous  silica  upon  evaporation. 


266  II.   MINERALS   WITHC 

B. — Fusible  from  1 — 5,  and  Non-volati 
PAKT  II. — Become  magnetic  after  heating  before  the  blowp; 

DIVISION  1. — Soluble  in  hydrochloric  or  nitric  acid  without  a  perceptible  residue  and  without 
see  Part  III,  Division  2,  p.  275. 


General  Characters. 

Specific  Characters, 

Name  of  Species. 

Oxides  and  hyd 
Difficultly    fu 
strongly  mag 
ing  B.  B.  in 
is  anhydrous 
water  in  the  c 

Streak  brownish-red  (Indian-red,  red-ocher). 
B^"  Compare  Turgite  and  Hematite  (p.  253). 

HEMATITE.(Earth 

non-crystalline.) 

sible.       Become 
netic  after  heat- 
R.  F.    Hematite 
the  others  give 
losed  tube. 

Streak  yellowish-brown  (yellow-ocher). 
Gothite  is  generally  found  in  distinct  crystals, 
while  the  others  are  not. 

GOETHITE. 

LIMONITE. 

(Brown  Hematite 

Xanthosiderite. 

Carbonate.—  Soluble  in  hot  HCI 
with  effervescence. 

In  the  closed  tube  becomes  black  and  magnetic. 

SIDERITE. 
(Spathic  Iron.) 

Sulphate*.—  Biuiura  chloride  when  added  to  the  dilute  HCI  solution  gives  a  pre- 
cipitate of  barium  sulpJiate  (p.  122,  §  1).  &JT  Concluded  on  next  page. 
When  heated  in  the  closed  tube  give  acid  water,  and,  generally,  the  odor  of 
sulphur  dioxide  is  perceptible  at  the  end  of  the  tube. 
The  tests  for  ferrous  iron  with  potassium  ferricyanide,  and  for  ferric  iron  with 
potassium  ferrocyanide,  are  made  in  dilute  HCI  solutions  as  directed  on  p.  85, 
§4. 

React  for  fer- 
rous iron,  but 
not  for  ferric. 

Wholly  soluble  in  cold  water. 

Melanterite. 
(Copperas.) 

Halotrichite. 

React  for  both 
ferrous  and 
ferric  iron. 

Wholly  soluble  in  cold  water. 

Romerite. 

Gives  with  the  salt  of  phosphorus  bead  a  chro- 
mium reaction. 

Knoxvillite. 

Partly  soluble  in  water,  leaving  generally  a  yel- 
lowish, ocher-like  residue. 

Botryogen. 

Voltaite. 

Metavoltaite. 

React  for  ferric 
iron,  but  not 
for  ferrous. 
Wholly  sol- 
uble in  cold 
water. 

Imparts  a  yellow  color  to  the  blowpipe  flame 
(sodium). 

Ferronatrite. 

Contain  no  other  base  than  iroa. 

Coquimbite. 

Queustedtite. 

Ihleite. 

React  for  ferric 
iron,  but  not 
for  ferrous. 
Insoluble,  or 
only  partially 
soluble,  in  cold 
water.  —  ContM 

Imparts  an  intense  yellow  color  to  the  blowpipe 
flame  (sodium). 

Sideronatrite. 

Does  not  give  water  in  the  closed  tube  at  low 
temperature.      Reacts  for  potassium  (p.  105, 

§D. 

Jarosite. 

With  ammonium  molybdate  gives  the  reaction 
for  a  phosphate  (p.  102,  §  1). 

Diadochite. 

DIVISION  1.—  Continued  on  next  page. 


METALLIC   LUSTER.  266 

or  only  Slowly  or  Partially  Volatile. 
n  the  reducing  flame. — Iron,  Cobalt  and  Nickel  Compounds. 
ing  gelatinous  silica  upon  evaporation.     For  details  concerning  the  method  of  making  this  test, 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystallu 
zation. 

3,0s. 

Indian-red. 

Dull. 

F.  Splintery. 

5-5.5 

4.2-5.0 

5-5.5 

Earthy. 
Reniform. 

30(OH)  = 
FesO,.H2O. 

Dark-  to  yel- 
lowish-brown. 

Adamantine  to 
dull. 

C.  Pinac.,  per. 
F.  Splintery. 

5-5.5 

4.37 

5-5.5 

Orthorh. 
II.   prism. 

34O3(OH)8  = 
2FeaO3.3H2O. 

Dark-  to  yel- 
lowish-brown. 

Silky  or  dull. 

F.  Splintery. 

5-5.5 

3.6-4.0 

5-5.5 

Mammill. 

Stalactitic 

eaO(OH)4  = 
FeaO3.2H20. 

Ocher-yellow. 

Silky  or  dull. 

2.5 

5-5.5 

Capillary. 
Earthy. 

eCOs. 

g,  Mn,  &  Ca  iso.w.Fe. 

Light-  to  dark- 
brown. 

Vitreous  to 
pearly. 

C.  Rhombo- 
hedral.  per. 

3.5-4 

3.8 

4.5-5 

Hex.  Rh. 
U.  cry  st. 

eSO4.7HaO. 

Apple-green. 

Vitreous. 

C.  Basal,  per. 

2 

1.9 

1. 
4.5-5 

Monocl. 

eAla(SO4)4.24H3O 

Yellowish- 
white. 

Silky. 

4.5-5 

MouocU 
Triclinic? 

'e"Fe"'a(SO4)4. 
12H,O. 

Light-  to  dark- 
brown. 

Vitreous. 

C.  Pinac.,  per. 

3-3.5 

2.15 

4.5-5 

Triclinic. 

Pe,Mg) 

[(Fe,Cr,Al)OH]7 
(SO4)8.5H2O? 

Greenish- 
yellow. 

C.  Basal,  per. 

4.5-5? 

Orthorh. 

Mg,Fe)(Fe.OH) 
(S04)a.7HaO. 

Hyacinth-  red. 

Vitreous. 

C.  Prismatic. 

2-2.5 

2-2.15 

4.5-5 

Monocl. 
U.   botry- 
oidal. 

'e"3(Fe.OH)a 

(Fe,Al)4(S04)10. 
14HaO? 
ler.  Ka,  Naa  iso.  w.  Fe. 

Oil-green  to 
greenish-black 

Resinous. 

F.  Uneven. 

3 

2.79 

1? 

Isometric? 

K2,Na2,Fe)'6Fe*', 
Fe'".OH)4(S04),a. 
16H2O? 

Yellow. 

2.5 

2.53 

4.5-5 

Hexag. 
Scales.     ' 

?a3Fe(SO4)3.3HaO. 

Pale  greenish- 
white. 

Vitreous. 

C.  Prismatic, 
perfect. 

2 

2.55 

1.5 

Hex.  Rh. 
U.  radiat. 

rea(SO4)3.9H2O. 

White,  green, 
amethystine. 

Vitreous. 

F.  Uneven. 

2-2.5 

2.1 

4.5-5 

Hex.  Rh. 
U.  cryst. 

"ea(SO4)8.10HaO. 

Reddish-violet 

Vitreous. 

C.  Pinacoidal, 
perfect. 

2.5 

2.11 

4.5-5 

Monocl. 

^e2(S04)3.12H2O. 

Orange-yellow 

1.8 

4.5-5 

Botryoi- 
dal. 

*aa(Fe.OH)(SO4)2. 
2HaO. 

Orange  to 
straw-yellow. 

Silky. 

3.  Pinacoidal. 

2-2.5 

2.35 

2 

Orthorh. 
Fibrous. 

£(Fe.2OH)3(SO4),. 
fa  iso.  w.  K. 

Ocher-yellow 
to  clove- 
brown. 

Vitreous. 

C.  Basal. 

2.5-3.5 

3.2 

4.5 

Hex.  Rh. 
U.  cryst. 

(Fe.OH)SO4. 
2FeP04.HaO. 

Yellow  or  yel- 
lowish-brown. 

Resinous. 

F.  Conchoidal. 

3 

2.03 

3? 

Monocl. 

(Page  267.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

B.— Fusible  from  1-5,  and  Non-volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  II. — Become  magnetic  after  heating  before  the  blowpipe  in  the 

reducing  flame. 

DIVISION  1,  continued 


II.   MINERALS  WITHO 
B.-Fusible  from  1-5,  and  Non-volati 

PART  IL-Become  magnetic  after  heating  before  the  blowpi 

DIVISION 


General  Characters. 


Yield  an  arsenical  mirror  when  placed  m  a 
closed  tube  with  a  fragment  of  charcoal  and 
heated  intensely  before  the  blowpipe  (p.  51,  $a). 


Sulphates,  concluded.— Barium 
chloride  when   added   to  th* 
dilute  HC1   solution   gives 
precipitate  of  barium  sulphate 

Whenheald'in  the  closed  tube 
give  acid  water,  and  gener 
Illy,  the  odor  of  sulphur  di 
oxide  is  perceptible  at  the  en. 
of  the  tube. 

React  tor  ferric  iron  but  not  for 
ferrous,  when  tested  as  directed 

Insoluble, 'or  only  partially  sol 
uble,  in  cold  water. 


Specific  Characters. 


Name  of  Species. 


Lossenite. 


Castanite. 


Copiapite. 


Utahite. 


in  the  case  of  Cyprusite,  which  contains  a 


Amarantite. 

Kcept  in  the  case  01  uyutw*,  «*" wTrnn 

ittle  aluminium,  these  minerals  have  only  iron Lbroferrite. 
M  the  base      When  heated  m  the  closed  tube  _ 

r£sidTof  firrie***  ^Mf1'  ^"U— . 
crushed,  gives  a  red  mark  (red-ocner;. 


Carphosiderite. 


Glockerite. 


Cyprusite. 


Arsenates.  —  When    heated 
tensely  B.  B.  in  a  closed  — 
with  a  fragment  of  charcoal  th 
arsenate   is    reduced    and    a_ 
arsenical  mirror  is  formed  (p. 
51,  £  a). 

Provided  the  mineral  contains 
much  calcium  it  is  best  to  heat 
in  a  closed  tube  with  Na2CO8 
and  charcoal-dust,  as  directed 
on  p.  51,  §6. 


iGive  a  blue   color    to  the  borax  bead  (cobalt). 
'     The  HC1  solution  has  a  rose  color.        . 

W  Annabergite  below  sometimes  contains  sum- 

cient  cobalt  to  give  a  blue  color  to 


V  iwiv/u     n 

•om.  A  iic  ^^  solutions  have  a 
green  coior.  '  Cabrerite  is  a  variety  of  anna- 
lergite  containing  magnesium 


Cabrerite 


Pharmacosiderit 


Arseniosiderite. 


DIVISION  1.— Concluded  on  next  page. 


'   METALLIC   LUSTER 

or  only  Slowly  or  Partially  Volatile. 

in  the  reducing  flame.-Iro»,  Cobalt  and  Niclcel  Compos 
-Continued. 


i  

Composition. 

.  •  

Luster. 



Cleavage  and 
Fracture. 

Hard- 
ness,     c 

Specific 
gravity. 

Fusi- 
ility. 

Crystalli- 
zation. 

ncertain.                 Yellowish-    to 
e,(As04),(SOO,  Q       reddlsbhrown 

itreous, 
greasy. 

2-3          J 

2.2-2.5 

2?     \ 

lassive. 
ieniform. 

re.OH)9(As04)6.      Yellow      to 
PbS04.12H20.  brownish-red. 

esinous. 

—  .  •  
itreous. 

Uneven. 

3-4 

J-2.5  C 

)rthorh. 

louocl. 
rismatic. 

ouccl 

3 

2.12 

.0-5 

!7f»  OFOSO4               (Jbestnut- 
QITT  Q                brown. 

WFe.OHMBU4)s.  Sulphur- 
17H2O.              yellow. 

early. 

Pinacoidal. 

2.5 

1 

.5-5 

"abular. 

tlex.  Rh. 
abular. 
'riclinic. 
Prismatic. 
kiouocl.? 
Tibrous. 

Hexag. 
Tabular. 

Hex.  Rh.? 
Reniform. 

Massive. 
Earthy. 

Hexag. 

Orange- 
I6Fe6S3Oaa.                      &  yellow 

ilky. 

Two  direc- 
tions,  per. 

— 

2.5 

28 

K  _ 
4.5-5 

4.5-5 

vr^a^   QTT  n    Orange-     to 
Fe.OH)bU4.o±i2u.    brownish-red. 

Resinous. 

Fe.  OH)S04.             Pale-yellow. 

Silky. 

2-2.5 

85 

4.5-5 

?e4(OH).(S04)s.       iHoney-      to 
4H2O.    ocher-yellow. 

Pearly. 

Basal,  per. 

3-3.5 

.2 

4.5-5 

?e6(OH)io(8O4)£  ^  Straw-yellow 

Resinous. 

Basal. 

4-4.5 

2.5-2.7 

4.5-5 

Brownish- 
<"e.2OH)2SO4.                     black 
3Fe(OH)3.H2O?          ocher-yellow 

Resinous. 
Earthy. 

4.5-5 

Al(FeO)7(SO4)5.        Yellow 
7HoO 

2 

1.75 

4.5-5 

Tabular. 
Monocl. 

^    /  *  ^  %  QTI  n     Crimson    to 
Co3(AsU4)2.oii2u.    |    peach-red. 

Pearly, 
vitreou 

Silky. 

C.  Pinac.,  per 



1.5-2.5 

2.5 

2.95 

2.5 

Prismatic 

3.1 

Fibrous. 
Monocl. 

H(Ni,Co)AsU4.         Qrayish-whi 

Nis(AsO4)2.8H2O.     Apple-green 

Pearly, 
vitreou 

C.  Pinac.,  pel 

.   1.5-2. 

4 

Capillary. 

Monocl. 
Prismat. 

(Ni,Mg)3(AsO4)a.      Upple-green. 

jw^OTDT"      "Green,  yellow 
"    (AsO4)3.6H2O.      browu,  red. 

Pearly. 

C.  Pinac.,  pei 

.  2 

2.95-3. 

L     4-5 

'  Adamantine 

F.  Uneven. 

2.5 

~  — 

2.9-3.0 

•  

3.2 

1.5-2 

_  • 
2-2.  1 

Isom.  leu 
U.  cryst. 
'.  Orthorh. 
*  U.  cryst. 
Orthorh. 

Pale-greeu    c 
FeAs04.2H2O.              brown. 

r  Vitreous. 

F.  Uneven.         3.5-4 

[Fe4(OH)6]Ca3          Black     to 
(AsO4)4  3H2O.   brownish-rec 

Sub-metalli 

F.  Uneven.       |  4.5 

3.57 

2-31 

Prismat. 
Fibrous. 

[K»5H5a^^IS2rtSL; 

to  Silky. 

Fibrous.            j  1""® 

3.5-3. 

3       3 

(Page  268.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

B.— Fusible  from  1-5,  and  Won- volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  II. — Become  magnetic  after  heating  before  the  blowpipe  in  the 

reducing  flame. 

DIVISION  1,  concluded. 


268 


II.   MINERALS  WITH01 
B.-Fusible  from  1-5,  and  Non-volatil 

PABT  IL-Become  magnetic  after  heating  before  the  blowpi 

DIVISION  1 


Name  of  Species. 


General  Characters. 


Contain  manganese.  — 
Impart  to  the  borax 
bead  in  O.  F.  a  red- 
dish -  violet  color. 
React  f  or  ferrous  iron 
when  the  dilute  HC1 
solution  is  tested  with 
potassium  ferrocyan- 
ide  (p.  85,  §  4). 
g"  Compare  the  phos- 
phates of  iron  and 
manganese  on  p.  276. 


little  or  no  water  in  the  closed  tube. 


Reacts  for  fluorine  (p.  76,  §2). 


'  tube  (OH  iso.  w.  F). 


no  water  in  t* 


Gives  water  in  the  closed  tube 


React  for  ferrous  iron 
(p.  85,  §4).  Contain 
little  or  no^manga- 
nese. 


Gives  water  in  the  closed  tube.     B.  B.  exfoliates  CMJJj-jg.    Beg, 
and  afterwards  fuses  on  the  edges. 


When  gently  heated  in  a  closed  tube,  Vivianite 
whitens,  while  Ludlamite  darkens.  Both 
darken  on  intense  ignition. 


Vivianite. 


*£«- 


Ludlamite. 


Chalcosiderite. 


If  a  drop  of  dilute  H2SO4  is  added  to  the  conceit 
trated  HCU  solution,  a  precipitate  of  calcium 
sulphate  will  be  formed. 


Borickite. 


alcioferrite. 


•SbS~  React  for  ferric  iron 
a  ^  fi  «  when  the  dilute  HC1 
.2  3  -c  £*  solution  is  tested  with 
^  «  >*  potassium  ferrocyan- 

ide(p.  85,  §4). 
I  All  of  the  minerals  in 
this      section      give 
water   in  the  closed 
tube. 


Beraunite, 
(Eleonorite.) 


Phosphosiderite. 


Contain  only  iron  as  the  base. 


arrandite. 


Jufrenite. 


Strengite. 


Koninckite. 


Cacoxenite. 


iron. 


METALLIC   LUSTER, 
or  only  Slowly  or  Partially  Volatile. 

n  the  reducing  flame.-/r<m,  Cobalt  and  NicM  Compounds. 


206 


Blue,  bluish-     Peariy  to 
3(P04)a.8HaO.          green  tc ,  vit] 


^e,Al)2(FeO)4       Light  to  dark    yitreou8. 
(P04)4.8H3O.      green1__l 


il,Fe)PO4.2H20.        green  or  yel 


'ic,(OH),P04.         Uolden-yellow  Silky. 

4^ilat>. 


;MgB204.                   Blackish-green Lul]   silky< 
Fe"Fe'"2O4.  nearly  black. 


Crystalli. 
zation. 

rthorh. 
.  mass. 

• 

[onocl. 
J.  mass. 

[onocl. 
3rismat. 


0  rthorh. 
Fig.  309, 
Page  207. 

Monocl. 
U.  prism. 


Vlonocl. 
U.  tabular 

Triclinic. 

Massive. 
Reniform 

Massive. 
Foliated. 

pheroid- 
al. 
Radiated^ 

)rthorh. 
J. Fibrous 
Vlonocl. 
U.  foliat. 

Orthorh. 

O  rthorh. 
U.  cryst. 

Radiated. 

Radiated. 

Orthorh. 
Fibrous. 

Massive. 
MammilL 


(Page  269.) 
II.  MINERALS   WITHOUT   METALLIC   LUSTER. 


B.— Fusible  from  1-5,  and  Non-volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  II. — Become  magnetic  after  heating  before  the  blowpipe  in  the 

reducing  flame. 

DIVISION  2. — Soluble  in  hydrochloric  or  nitric  acid,  and  give  gelatinons  silica  upon 
evaporation,  or  decomposed  with  the  separation  of  silica. 


269  II.   MINERALS   WITH01 

B.— Fusible  from  1—5,  and  Non-volat: 
PART  II. — Become  magnetic  after  heating  before  the  blowpi 

DIVISION   2.— Soluble  in  hydrochloric  or  nitric  acid  and  give  gelatinous   silica  upon   evapoi 
this  test  see  Part  III,  Division  3,  p.  278,  aud  Division  4,  p.  281. 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

E 

^a 

1 

M 
•S2 

|| 

>•§ 
b 

Gelatinize      with      hydro- 
chloric acid. 
JEJT*  Compare  Allanite   be- 
low, which  often  contains 
considerable  water. 

Cronstedtite  occurs  usually  in  crystals  with  tri- 
angular cross-section;  Thuringite  in  aggrega- 
tions of  minute  scales. 

Cronstedtite. 

Thuringite. 

Decomposed  by  hydro- 
chloric acid  with  the  sep- 
aration of  silica,  but 
without  forming  a  jelly. 

Radiated  or  foliated. 

Stilpnomelane. 
(Chalcodite.) 

Gives  a  reaction  for  chlorine  when  tested  as 
directed  on  p.  68,  §  3. 

Pyrosmalite. 

r  Give  little  or  no  water  in  the  closed  tube. 

Soluble  in  HC1  with  slight 
evolution  of  hydrogen 
sulphide. 

The  fine  powder  when  fused  with  a  little  Na2CO3 
on  charcoal  gives  a  coating  of  zinc  oxide. 

Danalite. 
(Helvite). 

Micaceous  or  foliated. 

Gelatinizes  with  HC1. 

LEPIDOMELANE. 

Slightly  attacked  by  HC1  with  separation  of 
silica. 

BIOTITE.     See 

the  micas,  p.  x'84. 

Readily  decomposed  by  HC1  with  separation  of 
silica.  The  solution  when  boiled  with  tin  be- 
comes violet  (titanium,  p.  127,  §2). 

Astrophylliie. 

Gelatinize  with  hydro  - 
chloric  acid.  Give  decid- 
ed reactions  for  both  fer- 
rous and  ferric  iron  (p. 

85,  §4). 

Fuses  quietly. 

llvaite. 
(Lievrite.) 

Swells  and  froths  during  fusion.  The  presence 
of  the  rare-earth  metals  may  be  detected  as 
directed  on  p.  65. 

Allanite. 

Gelatinizes  imperfectly. 
Characterized  by  ils  iso- 
metric crystallization. 

Reacts  mostly  for  ferric,  although  it  may  also 
contain  some  ferrous,  iron. 

ANDRADITE. 

(Calcium-iron 
Game 

Gelatinize.  Give  strong 
reactions  for  ferrous  iron, 
and  little  or  none  for 
ferric. 

Sometimes  magnetic  before  heating,  owing  to 
the  presence  of  included  particles  of  magnetite. 

Fayalite. 
(Iron  Chrysolite.) 

Closely  related  to  Fayalite,  but  differing  in  con- 
taining some  magnesium,  manganese  or  zinc, 
isomorphous  with  the  iron.  Test  for  manga- 
nese with  the  NaaCO3  bead,  for  zinc  by  fusing 
with  Na2CO3  on  charcoal,  and  for  magnesium 
as  directed  on  p.  91,  §  1,  b. 

Hortonolite. 

Knebelite. 

Roepperite. 

METALLIC   LUSTER.  269 

or  only  Slowly  or  Partially  Volatile. 

Q  the  reducing  flame. — Iron,  Cobalt  and  Nickel  Compounds. 

a,  or  decomposed  with    the  separation  of   silica. — For  details  concerning  the  method  of  making 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

,Fe"4Fe"'4Si3O20? 
iso.  w.  Fe. 

Black  to 
browuish- 
black. 

Vitreous. 

C.  Basal,  per. 

3.5 

3.35 

4 

Hex.  Rh. 
Hemimor; 

8Fe"8(Al,Fe)8 
Si6041? 

Olive-    to   pis- 
tachio-green. 

Dull. 

F.  Tough, 
uneven. 

2.5 

3.18 

< 

Compact. 
Scaly. 

((Fe,Mg)2(Fe,Al)2 
Si50,e? 

Greenish-  to 
yellowish- 
bronze. 

Pearly.bronze- 
like. 

C.  One  direc- 
tion. 

3 

2.75 

4.5 

Foliated. 

Velvety. 

(FeCl)(Fe,Mn)4 
(SiO'4)4. 

Pistachio- 
green  to 
brown. 

Pearly  to 
vitreous. 

C.  Basal,  per. 

4-4.5 

3.1-3.2 

3 

Hexag. 
Prismatic.. 

(R2S)(SiO4)3. 

=  Be,  Fe,  Zn  &  Mn. 

Flesh-red 
to  gray. 

Vitreous, 
resinous. 

F.  Uneven. 

5.5-6 

3.43 

4.5-5 

Isom.  Tet 

,H)2Fe"2(Fe,Al)2 
(Si04)3? 

Black, 
greenish-black 

Adamantine  to 
pearly. 

C.  Basal,  per. 

3 

3-3.2 

4.5-5 

Monocl. 

,H)2(Mg,Fe)2 
(Al,Fe)9(Si04)s. 

Green  to 
greenish-black 

Splendent, 
pearly. 

C.  Basal,  per. 

2.5-3 

2.8-3.1 

5 

Monocl. 

,Nu,H)4 
(Fe,Mn,Mg,Ca)4 

Ti(SiO4)4. 
iso.  w.  Si. 

Bronze-  to 
golden-yellow. 

Pearly. 

C.  Piuac.,  per. 

3 

3.3-3.4 

2.5-3 

Orthorh. 

iFe"2(Fe'".OH) 
(Si04)2. 

Iron-black. 

Black. 

F.  Uneven. 

5.5-6 

4.05 

2.5 

Orthorh. 
U.  prism. 

/2(R"'.OH)R'"a 

(Si04)3. 
'  =  Ca  &  Fe. 
"=Al,Fe,Ce,  La,&Di 

Brown-  to 
pitch-black. 

Gray. 

F.  uneven  to 
couchoidal. 

5.5-6 

3.5-4.2 

2.5 

Monocl. 
U.  mass. 

i3Fe2(Si04)3. 

,  Mn  &  Mg  iso.  w.  Ca; 
U  iso.  w.  Fe. 

Wine,  greenish 
yellow,  green, 
brown. 

Vitreous, 
adamantine. 

F.  Uneven. 

7 

3.75- 
3.85 

3.5 

Isometric. 
Figs.  97, 
105,  106, 

;2SiO4. 

Yellow  to  dark 
yellowfch- 
green. 

Resinous. 

C.  Pinacoidal. 
F.  Uneven. 

6.5 

4.32 

4 

Orthorh. 
U.  mass. 

'e,Mg,Mn)2SiO4. 

Yellow  to  dark 
yellowish- 
green. 

Resinous. 

C.  Pinacoidal. 

F.  Uneven. 

6.5 

4.03 

4.5 

Orthorh. 
U.  mass. 

e,Mn,Mg)aSiO4. 

Gray,  brown, 
green. 

Greasy. 

C.  Pinacoidal. 
F.  Uneven. 

6.5 

3.9-4.1 

3 

Orthorh. 
U.  masp 

e,Mn,Mg,Zn)2 
Si04. 

Yellow  to  dark 
yellowish- 
green. 

Greasy. 

C.  Pinacoidal. 
F.  Uneven. 

5.5-6 

3.95 

4.53 

Orthorh. 
U.  mass. 

(Page  270.) 
II.  MINERALS   WITHOUT   METALLIC   LUSTER. 


B.— Fusible  from  1-5,  and  Non-volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  II. — Become  magnetic  after  heating  before  the  blowpipe  in  the 

reducing  flame. 

DIVISION  3. — Insoluble  in,  or  only  slightly  acted  upon  by,  acids. 


U.   MINERALS   WITH( 

6.— ihisible  from  1—5,  and  Non-vola 

PART  II. — Become  magnetic  after  heating  before  the  blowp 

DIVISION  2. — Insohible  in,  or  oul 


General  Characters. 

Specific  Characters. 

Name  of  Specie 

Contains  tungsten.  —  Character- 
ized by  an  exceptionally  high 
specific  gravity. 

Test  for  tungsten  as  directed  on  p.  129,  §  2 
Colors  the  Na2CO3  bead  in  O.  F.  green  (man 
ganese). 

Wolframite. 

(Manganese  varie 

Micaceous. 

Easily  fusible.  Tinges  the  blowpipe  flame  red 
(lithium). 

Zinnwaldite. 

Difficultly  fusible. 

BIOTITE.       See 
micas,  p.  284. 

Distinguished  by  its  isometric 
crystallization. 

Fused  garnet  is  soluble  in  HC1,  and  yields  a  jelly 
on  evaporation. 

ALMANDITE, 

(Iron-aluminiurr 
Garuet.) 

Quietly  and  difficultly  fusible. 

Often  lias  a  peculiar  metal-like  schiller. 
J@F"  Com$tffdAtot?iopkylUU  (p.  287),   which  may 
become  magnetic  after  heating  B.B. 

Hypersthene. 

Fusible  B.  B.  with  intumescence, 
and  impart  a  decided  yellow 
color  to  tbe  flame  (sodium). 
The  perfect  prismatic  cleavage 
of  these  minerals  at  angles  of 
about  125°  and  55°  is  charac- 
teristic. 
Jg^~  Compare  these  members  of 
the  Amphil'ole  Group  of  min- 
erals with  those  on  p.  288. 

Contains  titanium  (p.  127,  §  2).  The  iron  is  chiefly 
ferrous  (test  as  directed  on  p.  86). 

JEnigmatite. 

The  iron  is  chiefly  ferrous. 

Arfvedsonite. 

Usually  has  a  fibrous  structure.  The  iron  is  both 
ferrous  and  ferric. 

Crocidolite. 

Contains  both  ferrous  and  ferric  iron. 

Riebeckite. 

Fuses  quietly  B.  B.,  coloring  the 
flame  yellow  (sodium).  The 
fused  globule  is  not  very  mag- 
netic. 

The  prismatic  faces  make  nearly  a  right  angle 
(93°)  with  one  another.  The  cleavage  is  not 
very  perfect. 

Acmite. 
(^girite.) 

Fuses  quietly,  and  without 
marked  flame  coloration. 

Contains  both  ferrous  and  ferric  iron  and  much 
calcium. 

Babingtonite. 

Compare  the  dark-green  and  black  varieties  of  Pyroxene,  Amphibole,  Tourmaline  and  oilier 
magnetic  when  heated  before  the  blowpipe. 


T   METALLIC   LUSTER. 

3,  or  only  Slowly  or  Partially  Volatile. 

in  the  reducing  flame.— Iron,  Cobalt  and  Nickel  Compounds. 
lightly  acted  upon  by,  acids. 


370 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

(Mn,Fe)W04. 

Black. 

Sub-metallic. 

C.  Pinac.,  per. 
F.  Uneven. 

5-5.5 

7.2-7.5 

4 

Monocl. 
U.  cryst. 

Monocl, 

(K,Li)3Fe"(A10) 
'AlF2)Al(SiO3)6. 

OH  iso.  w.  F. 

Gray,  brown, 
violet. 

Pearly, 

C.  Basal,  per. 

2.5-3 

2.8-3.2 

2.5-3 

(K,H)2(Mg,Fe)2 
(Al,Fe)2(Si04)3. 

Green  to 
greenish  -black 

Splendent, 
pearly. 

C.  Basal,  per. 

2.5-3 

2.8-3.1 

5 

Monocl. 

Fe"3Ala(Si04)3. 
Mn.Mg  &  Ca  iso.w.  Fe; 
Fe  iso.  w.  Al. 

Deep-red  to 
brownish-red. 

Vitreous. 

F.  Uneven. 

7-7.5 

4-4.15 

3 

Isometric,. 
Figs.  97, 
105,  106. 

Orthorh, 
U.  mass. 

;Mg,Fe)SiO,. 

Greenish- 
black,  bronze- 
brown. 

Bronze-like. 

C.  Piuac.,  per. 
F.  Uneven. 

5-6 

3.4-3.5 

5 

Uncertain. 
(Fe",Mn,Ca), 
(Fe'",Al),Na, 

(Ti,Si),0. 

Black. 

Vitreous. 

C.  Prismatic. 
F.  Uneven. 

6 

3.7-3.8 

3 

Tricliiiic* 

Monocl. 
Prismatic 

'Fe,Na2,Ca)4(SiO3)4 
Fea(Al,Fe)2Si2O12. 

Black. 

Vitreous. 

C.  Prism.,  per. 
F.  Uneven. 

6 

3.45 

2.5 

jN:iFe'"(SiO3)2. 
1(Fe",Mg,Ca)Si03. 

[ntense 
lavender-blue. 

Silky. 

F.  Fibrous. 

4 

3.2-3.3 

3.5 

fibrous. 
VIonocl. 

Honocl. 
:*rismatic~ 

^NaFe'"(SiO3)2. 
"j(Fe,Ca)SiO3. 

Black. 

Vitreous. 

C.  Prism.,  per. 

6? 

3.43 

3? 

NaFe'"(SiO3)2. 

Greenish-  to 
brownish- 
black. 

Vitreous. 

C.  Prismatic. 
F.  Uneven. 

6-6.5 

3.50 

3.5 

(  (Ca,Fe,Mn)SiO3. 
\  Fe2(Si03)3. 

jreenish-black 
to  black. 

Vitreous. 

C.   One   direc- 
tion, perfect. 
F.  Uneven. 

5.5-6 

3.35- 
3.40 

3-3.5 

Triclinic 
U.  cryst 

in  Division  5,  p.  283,  which  may  contain  sufficient  iron  to  cause  them  to  become  somewhat 


(Page  271.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

B.— Fusible  from  1-5,  and  Non-volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  glob- 
ule, and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

DIVISION  1. — After  intense  ignition  before  the  blowpipe,  either  in  the  forceps  or  on 
charcoal,  the  ignited  material  gives  an  alkaline  reaction  when  placed 
on  turmeric-paper. 

faction  a. — Easily  and  Completely  Soluble  in  Water. — In  part. 


271  II.   MINERALS   WIT] 

B.— Fusible  from  1—5,  and  Ifon-volat 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  gt 
DIVISION  1. — After  intense  ignition  before  the  blowpipe,  either  in  the  forceps  or  on  chare 

Section  a. — Easily  and  > 

N.B. — The  minerals  in  this  section  are  chiefly  salts  of  the  alkali  metals,  sodium  and  potassium, 
taste.     Flame  tests  will  generally  serve  to  identify  the  metals,  and  it  is  recommended  to  make  the  t 
(p.  115,  §  1),  but  only  those  containing  sodium  as  an  essential  constituent  give  an  intense  and  persistc 
color  when  viewed  through  rather  dark  blue  glass  (p.  105,  §  1). 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

Contain  chlorine.  —  The  aqueousjsolution, 
made  acid  with  HNO8,  gives  with 
silver  nitrate  a  precipitate  of  silver 
chloride. 

Combinations  of  a 
chloride  with  a  sul- 
phate. —  The  aqueous 
solution  made  acid 
with  a  littlee  HC1 
gives  a  precipitate 
with  barium  chlo- 
ride (p.  122,  §  1). 

Gives  a  slight  effervescence  when  a  fragment  is 
dropped  into  acid. 

Hanksite. 

Does  not  effervesce.  Gives  a  yellow  flame 
(sodium).  Reacts  tor  fluorine  (p.  75,  §  1). 

Sulphohalite. 

Does  not  effervesce.  Gives  a  violet  flame 
(  potassium). 

Kainite. 

Do  not  give  the  fore- 
going reaction  for  a 
sulphate. 

Gives  an  intense  yellow  flame  (sodium). 

HALITE. 

(Common  Salt.) 

Gives  a  violet  flame.  (potassium).  Sylvite  is  an- 
hydrous. Carnallite  contains  much  water. 

SYLVITE. 

Carnallite. 

Give  a  yellowish-red  flame  (calcium).  Deliquesce 
readily.  Tachydrite  melts  in  its  water  of 
crystallization. 

Hydrophilite. 

Tachydrite. 

Carbonates.  —  Effervesce    when 
treated  with  acids.    All  min- 
erals   in  this  section    give    a 
yellow  flame  (sodium).     Their 
aqueous  solutions  give  an  alka- 
line   reaction    with  turmeric- 
paper. 

Melts  in  its  water  of  crystallization  when  gently 
heated  in  a  closed  tube.  Water  63  per  cent. 

Natron. 
(Sal-soda.) 

Gives  water  and  carbon  dioxide  (p.  64,  §  2)  when 
gently  heated  (not  to  fusion)  in  a  closed  tube. 

Trona. 

Gives  water  (14  per  cent)  but  no  carbon  dioxide 
when  gently  heated  in  a  closed  tube. 

Thermonatrite. 

DIVISION  1,  Section  a. — Continued  on  next  page. 


UT   METALLIC   LUSTER.  2?J 

or  only  Slowly  or  Partially  Volatile. 

:le,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

the  ignited  material  gives  an  alkaline  reaction  when  placed  on  moistened  turmeric-paper. 

vletely  soluble  in  water. 

L  volatile  acids  (fiydrochloric,  carbonic,  sulphuric,  and  nitric).  Most  of  them  have  a  decided  saline 
on  platinum  wire  as  directed  on  p.  35.  Most  minerals  will  impart  some  3'ellow  color  to  the  flame 
rellow.  The  violet  flame  of  potassium,  which  may  not  be  very  evident,  has  a  decided  purplish-red 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

*a2SO4.2Na2CO3. 
KC1. 

Colorless   or 
white. 

Vitreous. 

C.  Basal. 
F.  Uneven. 

3-3.5 

2.55 

1.5 

Hexug 

Page  189. 

?a2SO4.NaCl. 
NaF. 

Colorless   or 
white. 

Vitreous. 

F.  Uneven. 

3.5 

2.50 

1 

Isometric. 
Fig.  97. 

gS04.KC1.3HaO. 

r 

Colorless   or 
white. 

Vitreous. 

C.  Pinacoidal. 

2.5-3 

2.05-2.2 

1.5-2 

Mouocl. 

**.* 

Colorless, 
white,  red, 
blue. 

Vitreous. 

C.  Cubic,  per. 

2.5 

2.13 

1.5 

Isometric. 
U.  cubic. 

01. 

Colorless    or 
white. 

Vitreous. 

C.  Cubic,  per. 

2 

1.9-2.0 

1.5 

Isometric. 
Figs.98.99 

gCla.KC1.6HaO. 

Colorless, 
white,  red. 

Vitreous. 

F.  Conchoidal. 

1 

1.8 

1-1.5 

Orthorh. 

iC!9. 

Colorless   or 
white. 

Vitreous. 

2.2 

1.5 

Isometric. 
Hex.  Rh. 

>lffCl2.CaCl2. 

12H2O. 

Wax-  to  honey- 
yellow. 

Vitreous. 

2.5 

1 

a2COa.lOHaO. 

Colorless, 
gray,  white. 

Vitreous. 

C.  Basal. 
F.  Conchoidal. 

1-1.5 

1.4-1.45 

1 

Monocl. 

a2CO3.HNaCO3. 
2H2O. 

Colorless, 
gray,  white. 

Vitreous. 

C.  Piuac.  ,  per. 
F.  Uneveg. 

2.5-3 

2.1-2.15 

1.5 

Mouocl. 

a2CO3.H2O. 

White,  gray, 
yellow. 

Vitreous. 

Somewhat 
sectile. 

1-1.5 

1.5-1.6 

1.5 

Orthorh 

(Page  272.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

B.— Fusible  from  1-5,  and  Non- volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  glob* 
ide,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

DIVISION  1. — After  intense  ignition  before  the  blowpipe,  either  in  the  forceps  or  on 
charcoal,  the  ignited  material  gives  an  alkaline  reaction  when  placed 
on  turmeric-paper. 

Section  a.— Easily  and  Completely  Soluble  in  Water. — Continued. 


II.    MINERALS   WITH' 
B.— Fusible  from  1—5,  and  Non-vola1 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  c 
DIVISION  1. — After  intense  ignition  before  the  blowpipe,  either  in  the  forceps  or  on  chai 

Section  a. — Easily  and  com]. 


General  Characters. 

Specific  Characters. 

Name  of  Species 

Sulphates.—  The  aqueous  solutions,  made  acid  with  HCI,  give  with  barium  chloride  a  white 
precipitate  of  barium  sulphate  (p.  122,  §  1),  but  do  not  give  the  reactions  of  the  preceding 
divisions.  The  test  on  silver,  after  the  reduction  of  the  sulphate  to  a  sulphide,  may  also  be 
applied  (p.  122,  §2). 

Give   no  water  in  the 
closed   tube,   and   are 
thus    distinguished 

from  the  sulphates  in 
the  following  sections. 

Gives  a  yellow  flame   (sodium),  which  appears 
purplish-red  when  viewed  through  blue  glass 
(potassium). 

Aphthitalite. 

Gives  a  yellow  fla'nle.     Contains  no  potassium. 

Thenardite. 

Gives  a  violet  flame  (potassium).     Reacts  for  am- 
monium (p.  43). 

Taylorite. 

Contain    aluminium.  — 
In    a  solution    made 
acid   with  HCI,  am- 
monia gives  a  precip- 
itate   of    aluminium 
hydroxide  (p  42,  §  2). 

B.  B.  swells  and  gives  a  yellow  flame  (sodium). 

Mendozite. 

B.  B.  swells  and  gives  a  violet  flame  (potassium). 

Kaliniie. 

(Potash  Alum.) 

Contain    magnesium.  — 
In   a   solution    made 
acid  with  HCI,   am- 
monia   produces    no 
precipitate  (provided 
the    solution    is    not 
too  concentrated),  but 
sodium       phosphate, 
added  to  the  solution 
made    alkaline    with 
ammonia,  gives  a  pre- 
cipitate of  ammonium 
magnesium        phos  - 
phate  (p.  91,  §1). 

Gives  the  odor  of  ammonia  when  heated  in  a 
closed  tube  with  lime  (p.  43). 

Boussingaultite. 

Give  no  pronounced  flame  coloration.     The  alka- 
line reaction  may  not  be  very  strong.     Have 
a  bitter  taste. 
l^T"  Compare  Sulphates,  Division  2,  p.  275. 

Epsomite. 

(Epsom  Salt.) 

Kieserite. 

Give  a  yellow  flame  coloration  (sodium). 

Loweite. 

Blodite. 

Give    a    violet    flame     coloration    (potassium}. 
Langbeinite  is  anhydrous. 

Langbeinite. 

Picromerite. 

Contain     sodium.  —  Im 
part  an  intense  yel- 
low color  to  the  blow- 
pipe or  Bunsen-burn- 
er  flames,  but  do  not 
give  the  reactions  of 
the    foregoing    divi- 
sions. 

Heated  in  a  bulb  tube  with  potassium  bisulphate 
yields  red  vapors  of  NO2  (nitrate  test),  p.  100. 

Darapskite. 

Gives  the  odor  of  ammonia  when  heated  in  a 
closed  tube  with  lime  (ignited  calcite). 

Lecontite. 

Gives  much  water  (55  per  cent)  in  the  closed  tube. 

Mirabilite. 

(Glauber  Salt.) 

Contain      potassium.  — 
Impart  a  violet  color 
to  the  flame,  but  do 
not  give  the  reactions 
of  the  foregoing  divi- 
sions. 

Has  a  sour  taste. 

Misenite. 

Sparingly  soluble  in  water.     Reacts  for  calcium 
(p.  60,  §  6). 

Syngenite. 

DIVISION  I.  Section  a. — Concluded  on  next  page. 


T   METALLIC   LUSTER. 

,  or  only  Slowly  or  Partially  Volatile. 

wle,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

1,  the  ignited  material  gives  an  alkaline  reaction  when  placed  on  moistened  turmeric-paper. 

ly  soluble  in  water. — Continued. 


273 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity 

Fusi 
bility. 

Crystalli- 
zation. 

K,Na)2S04. 

Colorless  or 
white. 

Vitreous. 

C.  Prismatic. 

3-3.5 

2.65 

1.5 

Hex.  Rh. 

TaaS04. 

Colorless, 
white, 
brownish. 

Vitreous. 

C.  Basal. 
F.  Uneven. 

2-3 

2.69 

1.5-2  Orthorli. 

£6(NH4)(S04)3. 

Yellowish- 
white. 

Vitreous. 

2 

1.5? 

Massive. 

JaAl(SO4)2.12H2O 

White. 

Silky-vitreous 

F.  Fibrous. 

3 

1.88 

1? 

Massive. 
Fibrous. 

LAl(SO4)a.12HaO. 

Colorless  or 
white. 

Vitreous. 

F.  Conchoidal. 

2-2.5 

1.75 

1 

Isom.Pyr. 

|U.  tibious 

IgSO4.(NH4)2SO4 
6HaO 

Colorless  or 
white. 

Vitreous. 

1.7 

1.5-2? 

Mor.ool. 

lgS04.7H20. 

Colorless  or 
white. 

VUreous. 

j.  Pinac.,  per. 
F.  Conchoidal. 

2-2.5 

1.7 

1 

Orihorh. 
Page  207. 

Monocl. 
Tetmg 

IgS04.H,0. 

White,  gray, 
yellow. 

Vitreous. 

C.  Prismatic. 

3-3.5 

2.56 

2-3? 

IgSO4.Na2SO4. 
2|H20. 

White,  yellow, 
red. 

Vitreous. 

C.  Basal. 
F.  Conchoidal 

2.5-3 

2.38 

1.5 

lgbO4.Na2SO4. 
4H20. 

Colorless  or 
white. 

Vitreous. 

F.  Uneven. 

2.5 

2.2-2.3 

1.5 

Monocl. 

Isometric. 
C1.5.p.219 

MgSO4.K2SO4. 

Colorless  or 
\vhite. 

Vitreous. 

F.  Conchoidal. 

3-4 

2.81 

1.5-2 

LgSO4.iv2SO4. 
6H20. 

Vhite. 

Vitreous. 

2.1-2.2 

1.5-2 

Monoei. 

a2S04.NaN03. 
H20. 

Colorless  or 
white. 

Vitreous. 

M.  Pinac.,  per. 

2-3 

2.20 

1? 

Monocl. 
Tabular. 

^a,NH4,K)2SO4. 
2H20. 

Colorless  or 
white. 

Vitreous. 

2-2.5 

1 

Orthorh. 

a2SO4.10H2O. 

Colorless  or 
while. 

Vitreous. 

.  Pinac.,  per. 

1.5-2 

1.48 

1.5 

Mouocl. 

KS04. 

olorless  or 
white. 

Vitreous  or 

silky. 

1 

Fibrous. 

aK2(S04)2.H20. 

olorless  or 
white. 

Vitreous. 

.  prism.,  per. 
<\  Conchoidal. 

2.5 

2.6 

1.5-2 

Vlonocl. 

(Page  273.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

B.— Fusible  from  1-5,  and  Non-volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  glob- 
ule, and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

DIVISION  1. — After  intense  ignition  before  the  blowpipe,  either  in  the  forceps  or  on 
charcoal,  the  ignited  material  gives  an  alkaline  reaction  when  placed 
on  moistened  turmeric-paper. 

Section  a. — Easily  and  completely  soluble  in  water. — Concluded. 

Section  b. — Insoluble  in  water,  or  difficultly  or  only  partially  soluble. — In  part. 


273  II.   MINERALS   WITHOU' 

B.— Fusible  from  1—5,  and  Non-volatile 

FABT  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  g\ 
DIVISION  1.— After  intense  ignition  before  the  blowpipe,  either  in  the  forceps  or  on  chare 

Section  a. — Easily  and 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

Nitrates.  —  When  heated  in  a 
bulb  tube  with  potassium  bi- 
sulphate,  red  vapors  of  N02 
are  given  off  (p.  100).* 

Gives  an  intense  yellow  flame  (sodium). 

SODA  NITER. 

Gives  a  violet  flame  (potassium). 

NITER. 

Gives  a  yellowish-green  flame  (barium).     Test 
on  platinum  wire  (p.  35). 

Nitrobarite. 

Berate.  —  Give  the  boracic  acid 
reaction  with  turmeric-paper 
(p.  56,  §  2). 

When  taken  up  in  the  loop  on  platinum  wire 
swells  when  first  heated,  and  fuses  finally  to  a 
clear  glass. 

* 

BORAX. 

Give  iodine  vapors  when  heated 
in  a  closed  tube. 

J3^~  Compare  the  difficultly  soluble  iodates,  Lau- 
tarite  and  Dietzeite,  in  the  next  section. 

*  Nitrates  of  calcium  and  magnesium,  containing  water  of  crystallization,  have  been  identified. 

Section  b. — Insoluble  in  water,  01 

N.B. — The  minerals  in  this  section  are  chiefly  salts  of  the  alkali-earth  metals,  calcium,  strontiu 
advantageously  in  identifying  the  metals,  and  it  is  recommended  to  make  the  tests  on  platinum  ^ 
hydrochloric  acid,  and  then  introducing  it  into  the  flame,  serves  in  many  cases  to  bring  out  the  col 

Silicates  and  other  compounds  which  do  not  properly  belong  to  this  section  at  times  give  an  al 
with  the  common  mineral  Galcite  (p.  289),  and  that  the  alkaline  reaction  is  due  to  truces  of  the  calci 
will  be  decomposed  and  a  misleading  alkaline  reaction  will  not  be  obtained. 


Carbonates.  —  Dissolve  in  dilute  hy- 
drochloric acid  with  effervescence 
(p.  62,  §1,  also  p.  63,  §1,  c). 

Give  water  in  the  closed 
tube.  [B.  B.  give  an 
intense  yellow  flame 
(sodium). 

When  treated  with  boiling  water,  calcium  carbo- 
nate separates,  and  the  soluble  sodium  carbo- 
nate renders  the  solution  alkaline.  Pirssonite 
exhibits  pyroelectricity  (p.  231). 

Gay-Lussite. 

Pirssonite. 

Ammonia  gives  a  precipitate  of  aluminium  hy- 
droxide when  added  to  the  dilute  HC1  solution 
(p.  42,  §  2). 

Dawsonite. 

Gives  water  in  the  closed 
tube,  but  does  not  con- 
tain sodium. 

The  dilute  HC1  solution  gives  a  precipitate  with 
barium  chloride  (p.  122),  and  a  residue  of  silica 
when  evaporated  to  dry  ness  (p.  109). 

Thaumasite. 

Give  no  water  in  the 
closed  tube. 

Gives  a  yellowish-green  color  to  the  flame 
(barium).  Test  on  platinum  wire  (p.  35). 

WITHERITE. 

Gives  an  intense  yellow  flame  (sodium).  Reacts 
for  chlorine  (p.  67,  §  1)  and  magnesium 
(P-  91,  §  1). 

Northupite. 

DIVISION  1. — Concluded  on  next  page. 


METALLIC   LUSTEB. 
only  Slowly  or  Partially  Volatile. 

le,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic 
the  ignited  material  gives  an  alkaline  reaction  when  placed  on  moistened  turmeric-paper. 
pletely  soluble  in  water. 


273 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

aN03. 

Colorless  or 
white. 

Vitreous. 

C.  Rhombo- 
hedral,  per. 

1.5-2 

2.29 

1 

Hex.  Rh. 

:N03. 

Colorless  or 
white. 

Vitreous. 

C.  Prism.,  per. 
F.  Conchoidal. 

2 

2.1-2.15 

1 

Orthorh. 
\j.  acicul. 
Isometric. 
C1.5,p.219 

a(N03)a. 

Colorless  or 
white. 

Vitreous. 

F.  Uneven. 

2.5 

1-1.5 

i'aaB4O7.10HaO/ 

Colorless  or 
white. 

Vitreous. 

C.  Pinac.,  per. 
F.  Conchoidal. 

2-2.5 

1.72 

1-1.5 

Monocl. 
I 

\ 

ficultly  or  only  partially  soluble. 

nd  barium,  with  volatile  acids  (carbonic,  sulphuric,  and  hydrofluoric).  Flame  tests  may  be  used 
as  directed  on  p.  35.  After  the  mineral  has  been  fused  on  the  wire,  touching  it  to  a  drop  of 
lore  decidedly. 

reaction  after  ignition.     It  will  generally  be  found,  however,  that  such  minerals  are  associated 
hich  permeate  minute  cracks  in  the  crystals.     If  such  minerals  are  thoroughly  fused  the  calcite 


faaCO3.CaC03. 
5HaO. 

Colorless 
white,  gray. 

Vitreous. 

C.  Prismatic. 
F.  Conchoidal. 

3-3 

1.99 

1.5 

Momocl. 
U.  cryst. 
Orthorh. 
Hemimor. 

JaaCO3.CaCO3. 
2H2O. 

Colorless, 
white,  gray. 

Vitreous. 

F.  Conchoidal. 

3-3.5 

2.35 

1.5 

Ta(A1.2OH)CO3. 

White. 

Vitreous, 
silky. 

F.  Longitu- 
dinal. 

3 

2.40 

4.5-5 

Monocl. 
Bladed. 
Radiated. 

'aCOs.CaSiOa. 
CaSO4.15HaO. 

White, 

colorless. 

Vitreous. 

F.  Splintery. 

3.5 

1.87 

5 

Hexag. 
Column., 
fibrous. 

iC03. 

Colorless, 
white,  gray. 

Vitreous. 

F.  Uneven. 

3.5 

4.3 

2.5-3 

1-1.5 

Orthorh. 
Twinned. 

HgC03.NaaCO,. 
NaCl. 

Colorless, 
white,  brown. 

Vitreous. 

F.  Conchoidal. 

3.5-4 

2.38 

Isometric. 
Fig.  96. 

(Page  274.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

B.— Fusible  from  1-5,  and  Non-volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  III.— "With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  glob- 
ule, and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

DIVISION  1. — After  intense  ignition  before  the  blowpipe,  either  in  the  forceps  or  on 
charcoal,  the  ignited  material  gives  an  alkaline  reaction  when  placed 
on  moistened  turmeric-paper. 

Section  b. — Insoluble  in  water,  or  difficultly  or  only  partially  soluble. — Concluded. 


274 


II.   MINERALS  WITHC 
B.— Fusible  from  1—5,  and  Non-vola 

PART  III.— With  sodium  carbonate  on  charcoal  do  not  give  a  metallic 
DIVISION  l.-After  intent  ignition  before  the  blowpipe,  either  in  the  forceps  or  on  char 

Section  &.— Insoluble  in  water,  or  dijjk 


General  Characters. 


S!' 


Specific  Characters. 


Ammonia  gives  a  precipitate  of  aluminium  hy 
droxide  when  added  to  the  HC1  solution. 


Ettringite. 


Give  much  water 
in  the  closed 
tube.  The  fine 
powder  is  readily 
soluble  in  boiling, 
dilute  HC1. 


Gives  no  decided  flame  coloration  when  heated 
alone  B.  B.  , 


s  ^23 


•5  I 


si* 


3  3W  i 


Gives  a  yellow  flame  (sodium). 


Give  a  violet  flame  (potassium),  seen  best  througl 
blue  glass.  Polyhalite  reacts  for  magnesium 
(p.  91,  §1). 


Give  little  or  no 
water  in  the 
closed  tube. 

Glauberite  is  read 
ily,    and    Anhy 
dritc  slowly,  sol 
uble    in    boiling 
dilute  HC1,  while 
Celestite  and  Ba 
rite  are  almost  in 
soluble. 


GYPSUM. 

(Alabaster.) 


Gives  a  yellow  flame  (sodium). 


Name  of  Specie 


Wattevillite. 


Polyhalite. 


Syngenite. 


Glauberite. 


Gives  no  decided  flame  coloration  when  heated jANHYDRITE. 
alone  B.  B. 


Gives  a  crimson  flame  (strontium). 


CELESTITE. 


Gives  a  yellowish-green  flame  (barium). 


ARITE. 

(Heavy  Spar.) 


jj^-  Compare  the  magnesium  sulphates  on  page  212,  some  of  which 
may  be  difficultly  soluble  in  water. 


Give  little  or  no 
water  in  the 
closed  tube. 


Easily  fusible.  Color  the  flame  yellow  (sodium). 
Powdered  cryolite  is  scarcely  visible  in  water 
because  of  its  low  index  of  refraction. 


Gives  a  reddish  flame  (calcium}.  Often  phos 
horesces  (p.  231)  and  decrepitates  when  heated 
u  the  closed  tube.  __________  _  . 


Give  acid  water  in 
the  closed  tube, 
often  accom 
panied  by  etch 
ing  of  the  glass 
and  a  deposit  o 
silica  (p.  77,  §  5) 
Compare  Pro 
sopite  ip.  290). 


lodatcs.— Fuse  and  give  iodin 
vapors  when  heated  in  a  closet 
tube. 


p 
iu 


Generally  decrepitate  to  a  fine  powder  whei 
heated  in  a  closed  tube.  Thomsenohte  occun 
in  rather  stout,  and  Pachnohte  in  very  slender 
prisms. 


Occurs    as    an    earthy    powder, 
sodium. 


Contains    n 


Dietzeite  is  readily  distinguished  by  its  reactio 
for  chromium  with  the  salt  of  phosphoii 
bead. 


RYOLITE. 


Chiolite. 


FLUORITE. 

(Fluor  Spar.) 


fhomsenolite. 


Pachnolite. 


Gearksutite. 


Lautarite. 


Dietzeite. 


METALLIC   LUSTER 
,  or  only  Slowly  or  Partially  Volatile. 

ule,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 
,  the  ignited  material  gives  an  alkaline  reaction  when  placed  on  moistened  turmeric-paper. 
or  only  partially  soluble. — Concluded. 


274 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

Ca.OH)s(SO4)3. 
2A1(OH)3.24H20? 

Colorless  or 
white. 

Vitreous. 

F.  Splintery. 

2-2.5 

1.75 

3 

Hexug. 
Needles. 

3aSO4.2HaO. 

Colorless, 
white,  gray. 

Vitreous. 

C.  3  directions. 
Pi.nac.,  per. 

2 

2.32 

3-3.5 

Monocl. 
Page  210. 

3aS04.Na2S04. 
4H20. 

tfe:iso.w.Ca,&Kw.Na. 

White. 

Silky, 
vitreous. 

1.81 

1.5-2 

Acicular. 

2CaSO4.MgSO4. 
K2SO4.2H20. 

Brick-ied  to 
yellow. 

Vitreous  to 
resinous. 

C.  Pinacoidal. 

F.  Splintery. 

2.5-3 

2.77 

2 

Monocl.  ? 
Column. 

CaK2(SO4)2.H20. 

Colorless  or 
white. 

Vitreous. 

C.  Pinac.,  per. 
F.  Conchoidul. 

2.5 

2.60 

1.5-2 

Monocl. 

CaS04.Na2SO4. 

Colorless, 
white,  gray. 

Vitreous. 

C.  Basal,  per. 
F.  Concboidal 

2.5-3 

2.75 

1.5-2 

Monocl. 
U.  tabul. 

CuS04. 

Colorless, 
white,  blue, 
gray,  red. 

Vitreous, 
pearly. 

C.  3  directions 
(pinacoidal) 
at  90°,  per. 

3-3.5 

2.95 

3-3.5 

Orthorh. 
U.  mass. 

SrSO4. 

Colorless, 
white,  blue, 
red. 

Vitreous, 
pearly. 

C.  Basal,  per.  & 
prismatic. 

3-3.5 

3.97 

3.5-4 

Orthorh. 
Page  202. 

BaSO4. 

Colorless, 
white,  blue, 
yellow,  red. 

Vitreous, 
pearly. 

C.  Basal,  per.& 
prismatic. 

3-3.5 

4.5 

4 

Orthorh. 
Page  201. 

Na3AlF,  = 
3NaF.AlF3. 

Colorless, 
snow-white, 
brownish. 

Vitreous  to 
greasy. 

C.  Pinacoidal. 
F.  Uneven. 

2.5 

2.97 

1.5 

Mouocl. 
U.  mass. 

5NaF.3AlF,. 

Snow-white. 

Vitreous. 

F.  Uneven. 

3.5-4 

2.9-3.0 

1.5 

Tetrag. 
U.  mass. 

CaFa. 

Colorless, 
violet,  green, 
yellow,  pink. 

Vitreous. 

C.  Octahedral, 
perfect. 
F.  Uneven. 

4 

3.18 

3 

Isometric. 

Figs.  95.  96, 
98,  112,  115. 

NaCaAlF,.HaO. 

Colorless, 
white,  brown. 

Pearly, 
vitreous. 

C.  Basal,  per. 
F.  Uneven. 

2 

2.93 

1.5 

Monocl. 
Cry  st.  & 
massive. 

NaCaAlF6.H2O. 

Colorless  or 
white. 

Vitreous. 

F.  Uneven. 

3 

2.98 

1.5 

Monocl. 
Prismatic 

CaF2.Al(F,OH)3. 
H2O. 

White. 

Dull. 

2? 

1.5-2 

Pulveru- 
lent. 
Earthy. 

Ca(I03)2. 

Sulphur- 
yellow  to 
colorless. 

Vitreous. 

C.  Prismatic. 
F.  Conchoidal. 

3.5-4 

4.59 

1.5 

Monocl. 
Prismatic 

7Ca(IO3)2.8CaCrO4. 

Golden-yellow 

Vitreous. 

F.  Uneven. 

3-4 

3.70 

1.5 

Mouocl. 
Tabular^ 

(Page  275.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

B.—  Fusible  from  1-5,  and  Non-volatile,  or  only  Slowly  or  Part-  ally 

Volatile. 

PART  III.  —  With  sodium  carbonate  on  charcoal  do  not  give  a  metallii  glob* 
ule,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 


DIVISION  2.  —  Soluble  in  hydrochloric  acid,  but  do  not  yield  a  jelly  or  a  residue  of  sili 
upon  evaporation.  —  In  part. 


275  II.   MINERALS   W1THO 

B. — Fusible  from  1—5,  and  Non-volati 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  g 

DIVISION  2. — Soluble  in  hydrochloric  acid,  but  do 

In  order  to  determine  whether  a  mineral  belongs  to  this  division  treat  one  or  two  ivory-spoonfi 
until  not  over  1  cc.  remains.  The  concentrated  solution  thus  obtained  should  be  a  clear  liquid  (no 
or  deposits  on  the  sides  of  the  tube,  it  should  go  wholly  into  solution  upon  addition  of  water  and  ws 


General  Characters. 


Specific  Characters. 


Name  of  Species. 


Sulphates. — The  dilute  HC1  solution  gives  with  barium  chloride  a  precipitate  of  barium  sulpha 
they  give  a  faint  and  not  very  decided  alkaline  reaction.  A  number  of  the  sulphates  of  ah. 
ignition  they  yield  an  infusible  muss  of  oxide  and  will  be  found,  therefore,  on  subsequent  page 


rQ    0 

*T3 

—  Q> 

Q)    OJ 

•^  ^    • 

•V  «>  « 

g^aooa 

ft 

c«- 
^ci  c 

1*§ 

§  °  - 

s  $  « 

.g  ,Q  y_ 
°   05    ° 

111 

1! 

>»£•£ 

1S£ 

Ss-3 

^J-S 
TB^  ^ 

x      o 

s^ 

g^a 

t«£ 

e^« 

•3** 

£  37; 
i  '*""  * 
J  —  s 
12  .2 
a  **>  ~ 

S'5!? 

i  =  i 

03  '~  J3 

2«F 

fcf 

|l| 
||| 

^  ~  ~ 

Contain  fluorine.  —  When 
heated  in   a  bulb  tube 
with    potassium    bisul- 
phate,  the  glass  is  etched 
and  a  deposit  of  silicti 
forms  on   the  walls  of 
the  tube  (p.  76,  §  2). 

Imparts  an  intense  yellow  color  to  the  blowpipe 
flame  (sodium). 

Durangite. 

Give  no  decided  flame  coloration.     The  concen- 
trated HC1  solution  gives  with  dilute  H2SO4  a 
precipitate  of  calcium  sulphate  (p.  59,  §3). 

Tilasite. 

Svabite. 

When  heated  in  R.  F.  on 
charcoal   with    a    little 
Na2CO3,  give  a  coating 
of  zinc  oxide. 

Gives  3  per  cent  of  water  in  the  closed  tube  (hy- 
droxyl,  p.  81,  §1,  b). 

Adamite. 

, 
Gives  "23  per  cent  of  water  in  the  closed  tube  (water 
of  crystallization,  p.  81,  §1,  b). 

Kottigite. 

Contain  manganese.  —  Im- 

Soluble in  HC1  with  evolution  of  chlorine. 

Synadelphite. 

Flinkite. 

Soluble  in  HC1  without  evolution  of  chlorine. 
Berzeliite  is  anhydrous;    the  rest  give  water  in 
the  closed  tube.      The  calcium  in  Berzeliite 
and  Brandtite  may  be  detected  by  adding  a 
drop  of  dilute  H2SO4  to  the  concentrated  HC1 
solution  (p.  59,  §  3). 

Berzeliite. 

part   a    reddish  -  violet 
color  to  the  borax  bead 
in  0.  F. 

Brandtite. 

Larkinite. 

Hemafibrite. 

Allactite. 

Contains  cobalt.  —  Imparts 
a  blue  color  to  the  borax 
bead. 

Reacts  for  calcium  when  a  drop  of  dilute  H2SO4 
is  added  to  the  concentrated  HC1  solution  (p. 
59,  §  3). 

Roselite. 

Contain   uranium.  —  Give  a  green  color  to  the  salt  of  phosphorus  bead  in 
R.  F.     Uranospinite  contains  calcium,  but  the  test  with  H2SO4  (p.  59, 
§  3)  must  be  made  very  carefully,  us  the  amount  is  small. 

Trogerite. 

Uranospinite. 

Contain  calcium,  but  do  n 
The  concentrated  HC1 
upon  addition  of  a  drop 

Adelite. 

ot  give  the  reactions  of  the  foregoing  divisions.  — 
solution  gives  a  precipitate  of  calcium  sulphate 
of  dilute  H2SO4  (p.  59,  §  3). 

Haidingerite. 

Pharmacolite. 

Ammonia  when  added  to  the  dilute  HC1  solution  gives  a  crystalline  pre- 
cipitate of  ammonium  magnesium  arsenaie. 

Hcernesite. 

DIVISION  2. — Continued  on  next  page. 


'   METALLIC   LUSTER.  275 

or  only  Slowly  or  Partially  Volatile. 

lie,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

yield  a  jelly  or  a  residue  of  silica  upon  evaporation. 

f  the  finely  pulverized  material  in  a  test-tube  with  from  3  to  5  cc.  of  hydrocloric  acid,  and  ooil 
ick  and  gelatinous,  indicating  a  silicate),  or,  in  case  any  solid  material  separates  from  the  solution 
ng. 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

}.  122,  §  1).     The  magnesium  sulphates  (p.  272)  might  possibly  be  referred  to  this  division,  because 
lium,  zinc,  manganese  and  nickel  may  swell  and  show  signs  of  fusion  when  first  heated,  but  after 
evoted  to  infusible  minerals. 

a(A!F)AsO4. 

3  &  Mn  iso.  \v.  Al. 

Light  to  dark 
orange-red. 

Vitreous. 

C.  Prismatic. 
F.  Uneven. 

5 

4.0 

2 

Monocl. 

a(MgF)AsO4. 

Gray  to  violet. 

Vitreous, 
greasy. 

C.  Pinac.,  per. 

4-5? 

Foliated. 

a4(CaF)(AsO4)3. 

H  iso.  \v.  F. 

Colorless. 

Vitreous, 
greasy. 

C.  Prismatic. 

3.5-3.8 

4.5-5 

Hexag. 

n(Zn.OH)AsO4. 

Pale  green, 
yellow,  violet, 
colorless. 

Vitreous. 

C.  Prismatic. 
F.  Uneven. 

3.5 

4.35 

3 

Orthorh. 

n,(AsO«)a.8HaO. 

Pale-red,  pink. 

Silky. 

C.  Pinac.,  per. 

2.5-3 

3.1 

3? 

Mouccl. 
Fibrous. 

Monocl. 
Orthorh. 

Mn,Al)AsO4. 
5Mn(OH)9. 

g£  Ca  iso.w.  Mn. 

Brownish- 
black  to  black. 

Vitreous, 
greasy. 

F.  Uneven. 

4.5 

3.45-3.5 

2-3? 

:nAsO4.Mn(OH)a. 

Greeuish- 
brown. 

Vitreous, 
greasy. 

4-4.5 

3.87 

2-3? 

!a,Mg,Mu), 

(As04)3. 

Sulphur-  to 
orange-yellow. 

Resinous. 

F.  Uneven.         5 

4.08 

3 

Isometric. 

a2Mn(AsO4)3. 
2HaO. 

Colorless  or 
white. 

Vitreous. 

F.  Uneven. 

5-5.5       3.67 

2.5-3 

Triclin.c. 

[n(Mn.OH)AsO4. 

Flesh-,  rose-,  or 
yellowish-red. 

Greasy. 

C.  Prismatic. 
F.  Uneven. 

4-5          4.18 

2 

Monocl. 

:n3(AsO4)a. 
3Mn(OH)2. 

2? 

Orthorh. 

ln3(AsO4)2. 

4Mn(OH)2. 

Brownish-red. 

Vitreous, 
greasy. 

C.  One  direc. 
F.  Uneven. 

4.5           3.84 

2? 

Monocl. 

XCo,Mg)8(AsO4)a. 
2H20. 

Rose-red. 

Vitreous. 

C.  Pinacoidal. 

3.5 

3.5-3.6 

3 

Triclinic. 

JO2)3(AsO4)2. 
12H9O. 

Lemon-yellov?. 

C.  Pinac.,  per. 

3.3 

9  ~     Monocl. 
^     U.  tabul. 

a(UO,,)(As0^o  B,gh,g,,el, 

C.  Basal,  per. 

2-3          3.45 

Orthorh. 
U.  tabul. 

a(Mg.OH)AsO4       Gray. 

5 

3.76 

Monocl. 

:CaAsO4.H2O. 

White. 

Pearly, 
vitreous. 

C.  Pinac.,  per. 

1.5-2.5 

2.85 

2.5     Orthorh. 

:CaAsO4.2H2O. 

White  or 
grayish. 

C.  Pinac.,  per. 
F.  Uneven. 

2-2.5 

2.6-2.7 

0  .    jMonocl. 
-*>0     U.fibrous. 

[g3(AsO4)a.8H20. 

Snow-white. 

Pearly. 

C.  Piuac.,  per.  1 

2.47 

2-3  ?  Monocl, 

(Page  2?'6.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

B.— Fusible  from  1-5,  and  Non-volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  glob- 
ule, and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

DIVISION  2.— Soluble  in  hydrochloric  acid,  but  do  not  yield  a  jelly  or  a  residue  of  silica 
upon  evaporation. — Continued. 


276 


II.   MINERALS   WITHC 
B.— Fusible  from  1—5,  and  Non-volati 

PABT  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  g 
DIVISION  2. — Soluble  in  hydrochloric  acid,  but  do  not  yie 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

phosphomolybdate  when  a  few  drops  of  the 
5  (p.  102,  §  1).  When  ammonium  molybdate 
i,  often  seen  only  after  moistening  the  assay 
phate.  $&~Phosphates  concluded  on  next  page. 

Contain  uranium.  —  Im- 

Autunite and  Uranocircite  react  for  calcium  and 
barium,  respectively,  when  their  HC1  solutions 
are  treated  with  dilute  H8SO4  (p.  59,  §3,  and 
p.  52,  §3). 

Autunite. 

part  a  green  color  to 
the     salt    of     phos- 
phorus bead  in  R.  F. 

Uraiiocircite. 

Phosphuranylite. 

Contain     manganese.  — 
Impart     a    reddish  - 
violet    color    to    the 
borax  bead  in  O.  F. 
Ferrous    iron    (isomor- 
pl  ous  with  the  man- 
ga aese)   is  present  in 
almosi;  all  eases.  Test 
with  potassium  ferri- 
cyanide    as    directed 
on  p.  15,  §  4. 
When  calcium  is  pres- 
ent it  may  be  detected 
by  adding  a  drop  of 
dilute  H2SO4  to  the 
concentrated  HC1  so- 
lution (p.  59,  §  3). 

Gives  a  red  Game  (lithium),  tried  best  on  platinum 
wire  (p.  35). 

Lithiophilite.     See 
triphylite,  p.  268. 

Give  an  intense  yellow  flame  (sodium),  and  no 
water  or  only  a  little  in  the  closed  tube. 

Natrophilite. 

Dickinsonite. 

Fillowite. 

B.  B.  cracks  open,  swellstaud  whitens,  then  fuses 
to  a  dark  brown  or  black  mass. 

Eosphorite.    See 
childrenite,  p.  268. 

Fuses  to  an  orange  or  reddish-yellow  globule. 

Hureaulite. 

Jive  a  yellow  precipitate  of  ammonium 
ion  are  added  to  ammonium  molybdaU 
d,  the  pale  Uuish-green  flame  colorntioi 
ric  acid,  mny  be  used  to  identify  tho  phos 

Contains  much  calcium. 

Fairfieldite. 

Contains  only  traces  of  calcium. 

Reddingite. 

Contain  much  calcium. 
—  In  the  concentrated 
HC1  solution  a  pre- 
cipitate   of     calcium 
sulphate   forms  upon 
addition  of  a  drop  of 
dilute  sulphuric  acid 
(p.  59,  §3). 
HJT  Compare  Bobierrite 
(p.  277),   which   may 
contain  a    little  cal- 
cium. 

Anhydrous.  Gives  a  slight  reaction  for  fluorine 
(p.  76,  §  2),  and  often  also  for  chlorine  (p.  67, 
§D- 

APATITE. 

Gives  a  little  water  when  intensely  heated  in  the 
closed  tube,  and  also  vapors  of  hydrofluoric 
acid  which  etch  the  glass  (p.  77,  §  5). 

Herderite. 

Give  a  little  water  in  the  closed  tube  (not  over 
7  per  cent).  That  the  quantity  of  water  is 
small  may  be  determined  by  comparing  the 
closed-tube  test  with  one  made  upon  an  equally 
lanre  fragment  of  gypsum  which  has  21  per 
cent  of  water. 

Hydro-herderite. 

Cirrolite. 

Monetite. 

sf  If 

<2  ^Z  +*  & 

liM 

*M.22  £ 

Collophanite. 

Give  much  water  in  the  closed  tube  (20  per  cent 
or  over).  Compare  the  quantity  of  water  with 
that  obtained  from  gypsum  which  has  21  per 
cent. 

Isoclasite. 

Brushite. 

DIVJSION  2.— Concluded  on  next  page. 


METALLIC   LUSTER, 
or  only  Slowly  or  Partially  Volatile. 
le,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

y  or  a  residue  of  silica  upon  evaporation. — Continued. 


276 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard. 

tiess. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

UO2)3(PO4)2.       Lemon-  to  sul-  Pearly  to  sub- 
8H2O.     plmr-yellow.      adamantine. 

C.  Basal,  per. 

2-2.5 

3.05-3.2 

Q       Oil  horn. 
Tabular. 

U02)2(P04)2. 
8H3O. 

Yellowish- 
green. 

Pearly  to  sub- 
adamantine. 

C.  Basal,  per. 

2-2.5 

3.53 

Q  9    ;Orthorh. 
'     |  Tabular. 

D2)3(P04)2.6H2O 

Deep  lemon- 
yellow. 

Pearly. 

3-4? 

Pulveru- 
lent. 

Mn,Fe)PO4. 

Salmon-color,   „    • 
clove-brown.  Kesmous. 

C.  Basal,^?-.  &  A  K_  K 
phmcoidal.    i4'5" 

3.48 

2-2.5 

Orthorh. 

(Mn,Fe)P04. 

Deep  wine- 
yellow.  Resinous. 

C.  Basal,  per. 

4.5-5 

3.41 

2-2.5 

Orthorh. 

u,Fe,Ca,Na2)3 
(PO4)2.iH20. 

Olive-,  oil-,  or  sVitreous, 
grass-green.                 pearly. 

C.  Basal,  per. 

3.5-4 

3.34 

2.5-3 

Jionocl. 
Foliated. 

i,Fe,Ca,Nas), 
(P04)..iH,0. 

Wax-yellow  to 
brown. 

Greasy. 

C.  Basal. 
F.  Uneven. 

4.5 

3.43 

2.5-3 

Monocl. 

u,Fe)(A1.2OH) 

PO4.H2O. 

Delicate  rose- 
pink. 

Vitreous, 
resinous. 

D.  Pinacoidal. 
F.  Uneven. 

5 

3.12 

4 

Orthorh. 

Mu,Fe)5(P04)4. 
4H20. 

Pale-rose,     or- 
ange, brown. 

Vitreous, 
greasy. 

C.  Piuacoidal. 

5 

3.18 

3 

Monocl. 

!Mn(PO4)3.2H2O 
so.  \v.  Mn. 

Colorless  to 
greenish-white 

Pearly  to  sub- 
adamantine. 

C.  Pinac.,  per. 

3.5 

3.15         4-4.5 

Tricliuic. 

3(P04)2.3H2O. 

so.  w.  Mn. 

Pale-rose  to 
brown. 

Vitreous  to 
resinous. 

F.  Uneven.         3-3.5 

3.10 

2.5-3 

Orthorh. 

(CaF)(P04)3. 

so.  \v.  V. 
arely  Mn  iso.  w.  Ca. 

Green    blue,      yitr 
violet,  brown,                crreasv 
colorless.                        greasy. 

C.  Basal.           1  ^ 
F.  Uneven. 

3.15 

5-5.5 

Hexag., 
Page  189. 

;Be(OH,F)]PO4. 

White  to  pale- 
green  or 
yellow. 

Vitreous  to 
resinous. 

F.  Uneven. 

5 

3.00 

4 

Monocl. 

Be.OH)P04. 

White       •ale- 
green,  $eliow. 

Vitreous  to 
resinous. 

F.  Uneven. 

5 

2.95 

4 

Monocl. 

,.OH)3A12(P04)3. 

White  to  pale 
yellow. 

Vitreous. 

F.  Uneven. 

5-6 

3.08 

4 

Massive. 

!aPO4. 

Yellowish- 
white. 

Vitreous. 

C.  Piuacoidal. 
F.  Uneven. 

3.5 

2.75 

3 

Tridinic. 
Am  or  ph. 
Monocl. 
Monocl. 

3(P04)2.H2O. 

Colorless, 
white,  yellow. 

Dull. 

F.  Couchoidal. 

2-2.5 

2.70 

4.5-5  ? 

Ca.OH)PO4. 
2H20. 

Colorless  or 
white. 

Vitreous, 
pearly. 

C.  Pinac.,  per. 

1.5 

2.92 

4? 

)aPO4.2H2O. 

Colorless  to 
pale-yellow. 

Vitreous, 
pearly. 

C.  Piuac.,  per. 

2-2.5 

2.20 

3 

(Page  277.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

B.— Fusible  from  1-5,  and  Non-volatile,  or  only  Slowly  or  Partially 

Volatile. 

PAKT  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  glob- 
ule, and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

DIVISION  2. — Soluble  in  hydrochloric  acid,  but  do  not  yield  a  jelly  or  a  residue  of  silica 
upon  evaporation. — Concluded. 


277 


II.    MINERALS   WITHO 
B.— Fusible  from  1—5,  and  Non-volati 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  g* 
DIVISION  2. — Soluble  in  hydrochloric  acid,  but  do  not 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

Phosphates.  —  Concl  tided. 
Do  not  give  the  foregoing  reac- 
tions for  uranium,  manganese 
and  calcium. 
$HT  A    few    phosphates    which 
are  difficultly  soluble  in  HCI 
will   be  found  in  Division   5, 
p.  283. 

Gives  an  intense  yellow  flame  (sodium).     Anhy- 
drous. 

Beryllonite. 

Gives  a  reaction^for  fluorine  (p.  76,  §2).  Contains 
little  or  no  water. 

Wagnerite. 

[n  the  closed  tube  give  water  and  the  odor  of 
ammonia. 

Struvite. 

Stercorite. 
(Salt  of  Phosphorus 

Gives  a  coating  of  oxide  of  zinc  when  heated  with 
a  little  NaaCO3  on  charcoal  in  R.  F. 

Hopeite. 

Reacts  for  boron  (p.  56,  §  2). 

Lilneburgite. 

Ammonia,  when  added  to  the  dilute  HCI  solu- 
tion, gives  a  crystalline  precipitate  of  ammo- 
nium magnesium  phosphate. 

Bobierrite. 
(Hautefeuillite, 
when  containing 
Ca  iso.  w.  Mg.) 

,2  """  £  JD 

Kit 

lilJ 

s   -°  « 

-«  bo2 
§1.5  5 

Give  little  or  no  water 
in  the  closed  tube. 
The  remaining  bo- 
rates  contain  water. 

Colors  the  flame  green.    Reacts  for  chlonnevfken 
fused  with  NaaCO3,  dissolved  in  dilute  HNO8 
and  tested  with  silver  nitrate  (p.  67,  §  1). 

Boracite. 

B.  B.  gives  a  green  flame.     Reacts  for  potassium 
(p.  105,  §  I,  c). 

Rhodizite. 

Imparts  a  reddish-violet  color  to  the  borax  bead 
in  O.  F.  (manganese). 

Pinakiolite. 

Readily  soluble  in 
water. 

B.  B.  fuses  with  much  swelling  and  imparts  a 
yellow  color  to  the  flame  (sodium). 

BORAX. 

Slowly  volatilizes  B.  B.,  tinging  the  flame  green. 

Sassolite. 
(Boracic  Acid.) 

Imparts  a  reddish-violel 
color  to  the  borax  bead 
in  U.  F.  (manganese). 

Colors  the  flame  green. 

Sussexite. 

Con  tain  calcium.  —  Thedi- 
lute  HCI  solution,  after 
being  made  alkaline 
with  ammonia,  gives  a 
precipitate  with  am- 
monium oxalate  (p.  60 
§6).  N.B.—  If  the  HCI 
solution  is  too  concen- 
trated the  addition  of 
ammonia  may  cause  a 
precipitate  of  calcium 
borate. 

B.  B.  exfoliates,  crumbles  and  colors  the  flame 
green. 

Colemaniie. 

B.  B.  fuses  to  a  clear  glass,  and  colors  the  flame 
green. 

Hydroboracite. 

Borates.—  Turmeric-pape 
solution  of  the  mi 
outside  of  a  test-tube  < 
dish-brown  color.  JM 
blowpipe  flame. 

B.  B.  colors  the  flame  yellow  (sodium). 

Ulex.te. 

B.  B.  colors  the  flame  reddish-yellow  (?). 

Bechilite. 

Contain  magnesium.  — 
The  dilute  HCI  solution 
when  made  strongly 
alkalinewith  ammonia 
gives  a  precipitate  with 
sodium  phosphate  (p 
91,  §1). 

B.  B.  cracks  open,  glows  and  fuses  to  a  pale, 
horn-like,  brownish-gray  mass. 

Szaibelyite. 

B.  B.    fuses    quietly   at    3,   coloring   the    flame 
green. 

Pinnoite. 

B.  B.  fuses  very    easily  and    colors    the  flame 
preen. 

Heiritzite. 

Molybdates 
test  desc 

—Give  the  reduction 

The  dilute  HCI   solution,    made  alkaline   with 
ammonia,  gives  a  precipitate  either  with  am- 
monium oxalate  (p.  60,  §  6,  Powellite)  or  with 
sodium  phosphate  (p.  91,  §1,  Belonesite). 

Powellite. 

ribed  on  p.  96,  §  4. 

Belonesite. 

Sulphides.—  Give  the  odor  of  sul- 
phurous anhydride,  SO2,  when 
roasted  in  the  open  tube. 

Sphalerite  ZnS,  which  becomes  rounded  B.  B.  owing  to  the  volai 
Alabandite  MnS,  and  Hauerite  MnS2,  are  classed  on  p.  253. 

METALLIC   LUSTER, 
or  only  Slowly  or  Partially  Volatile. 

lie,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic, 
d  a  jelly  or  a  residue  of  silica  upon  evaporation. — Concluded. 


277 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 

ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

aBePO4. 

Colorless  or 
white. 

Vitreous, 
pearly. 

3.  Basal,  per. 
F.  Conchoidal. 

5.5-6 

2.84 

3-3.5 

Orthorh. 

g(MgF)P04. 

Pale-yellow, 
gray  or  red. 

Vitreous. 

?.  Uneven. 

5-5.5 

3.06 

3.5-4 

Monocl. 

H4MgPO4.6H2O. 

White,  yellow, 
brown. 

Vitreous. 

?.  Uneven. 

2 

1.65 

3 

Orthorh. 
ELemimor. 

(NH4)NaP04. 
4H20. 

White,  yellow, 
brown. 

Vitreous. 

2 

1.61 

1 

VIonocl. 

n3(P04)2.4H20. 

Grayish-white. 

Vitreous. 

3.  Piuac.,  per. 
F.  Uneven. 

2.5-3 

2.75-2.8 

3-4? 

Orthorh. 

[g3(P04)2.B203. 
8H20. 

White. 

2.05 

Fibrous. 
Earthy. 

[g3(P04)2.8H20. 

a  iso.  w.  Mg. 

Colorless  or 
white. 

C.  Pinacoidal. 

2.5 

2.43 

Monocl. 

[g7C!2B16030.  *" 

Colorless, 
white,  gray, 
green. 

Vitreous. 

F.  Conchoidal. 

7 

2.9-3.0 

3 

Isom.  Tet. 
Page  175. 

:(A10)2(B02)3. 

Colorless  or 
white. 

Vitreous. 

8 

3.41 

4.5-5 

Isom.  Tet. 

MgBiO4. 
Mu"Mn'"204. 

Blnck. 

Sub-metallic. 

C.  Pinacoidal. 

6 

3.88 

5 

Ortborh. 
Tabular. 

ra2B4O7.10H2O. 

Colorless  or 
white. 

Vitreous. 

C.  Pinac.,  per. 
F.  Gonohoidal. 

2-2.5 

1.75 

1-1.5 

Mouocl. 

5(OH)3. 

Colorless  or 
white. 

Pearly. 

C.  Basal,  per. 

1 

1.48 

0.5 

Tricliuic, 
U.  tabular 

[(Mn,Mg,ZD)BO3. 

Gray. 

Silky. 

F.  Splintery. 

3 

3.12 

2.5 

Orthorh.? 
B'ibrous. 

Ja2B6O31.5H2O. 

Colorless  or 
white. 

Vitreous. 

0.  Pinac.,  per. 
F.  Uneven. 

4-4.5 

2.42 

1.5 

Monocl. 

!aMgB6On.6H2O. 

White. 

Vitreous, 
silky. 

C.  One  direc- 
tion. 

2 

1.9-2.0 

1.5? 

Fibrous, 
foliated. 

JaCaB5O8.8H2O. 

White. 

Silky. 

1 

1.65 

1.5 

Fibrous. 

kB4O7.4H2O. 

1.5? 

Massive. 

Ig^On.HHsO. 

White  to 
yellow. 

3-4 

3.0 

Nodular. 
Acicular. 

>IgB204.3H20. 

Sulphur-  or 
straw-yellow. 

Vitreous. 

3-4 

3.3 

3 

Tetrag. 
Cl.  20,  p.219. 

CMg,B11019.7H20. 

Colorless  or 
white. 

Vitreous. 

C.  Pinac.  & 
basal,  per. 

4-5 

2.13 

1 

Monocl. 

Tetrasr. 
Cl.  20,  p.219 

'aMoO4. 
V  iso.  w.  Mo. 

Colorless, 
green,  yellow. 

Resinous. 

F.  Uneven. 

3.5 

4.52 

4 

VIgMo04. 

Colorless, 
white. 

4-5 

Tetrag. 

ation  of  the  zinc,  but  does  not  fuse,  is  classed  on  p.  292.     The  dark-colored  manganese 

sulphides 

(Page  278.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

B.— Fusible  from  1-5,  and  Won- volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  glob- 
ule, and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

DIVISION  3.  —  Soluble  in  hydrochloric  acid,  and  yield  gelatinous  silica  upon  evaporation 
Section  a.— In  the  closed  tube  give  water. 


II.   MINEKALS   WITHO 
278 

B.— Fusible  from  1—5,  and  Non-vola 

PAKT  III.— With  sodium  carbonate  on  charcoal  do  not  give  a  metallic , 

DIVISION  3.— Soluble  in  hydrochloric  aci( 

In  order  to  determine  that  a  mineral  belongs  to  this  division  treat  one  or  two  ivory-spoonfuls 
over  1  c  c  remains.  The  mineral  should  go  wholly  into  solution,  unless  difficultly  soluble,  and  T 
gelatinous  silicic  acid  (p.  108,  §  1).  The  silicic  acid  thus  separated  will  not  go  into  solutior 

Section  a.— In  the  closed  tube  give  water.— Silicat 


General  Characters. 


Specific  Characters. 


B.  B.  fuses  to  a  clear 
closed  tube. 


glass,  coloring  the  flame  green.     Gives  a  little  water  in  the 


DATOLITE. 


The  dilute  HC1  solution  gives  with  H2SO4  a  precipitate  of  barium  sulphate. 


Imparts  a  reddish-violet  color  to  the  borax  bead  in  O.  F.  (manganese). 
decidedly  micaceous  structure. 


Has  a 


Gives  a  coating  of  oxide  of 
when  fused  on  charcoal  with 
a  little  Na3COs. 


zinc  B.  B.  whitens  and  fuses  with  difficulty. 


B.  B.  fuses  to  a  yellow  globule. 


Contain  the  carbonate  radical. — 
A  fragment  dissolves  with 
effervescence  in  warm  dilute 
HC1 


B.  B.  swells,  Iruilis  and  fuses  to  a  vesicular 
globule.  In  the  closed  tube  whitens  and  gives 
water. 


Contain  little  or  no  calcium. — 
After  separation  of  the  silica 
and  alumina  (p.  110,  §  4),  am- 
monium oxalate  produces  little 
or  no  precipitate  in  the  am- 
moniacal  nitrate  (p.  60,  §  G). 


Fuses  quietly  to  a  clear,  transparent  glass. 


Contain  aluminium  and  calcium. 
— In  the  HC1  solution,  after 
separation  of  the  silica  (p.  108, 
§1),  ammonia  produces  a  pre- 
cipitate of  aluminium  hy 
droxide  (p.  42.  §  2),  and  in  the 
filtrate  ammonium  oxalate  pro- 
duces a  precipitate  of  calcium 
oxalate  (p.  60,  §  6). 

Compare  Allaniie  (p.  280 
which  may  contain  water  if 
impure.  * 


Gives  the  reactions  of  the  rare-earth  metals  (p.  65) 


Fuses  easily  to  a  white  enamel. 


Fuses  to  a  glassy  enamel.     Gives  a  reaction  for 
magnesium  (p.  91, 


Name  of  Specie 


Edingtonite. 


Ganophyllite. 


CALAMINE. 


Clinohedrite. 


Cancrinite. 


Jenosite. 
(Kainosite.) 


NATROLITE. 


Hydronephelite. 


Spadaite. 


Fuses  to  a  voluminous,   frothy  slag.     Exnibits|Scolecite. 
py roelectricity  (p.  231). | '_ 


Fuse  with  intumescence  to  white  vesicular 
globules.  Do  not  exhibit  pyroelectricity. 

Mesolite  contains  both  the  uatrolite  and  scolecite 
molecules. 


Mesolite. 


fhofhsonite. 
(Comptonite.) 


^evynite. 


Occurs  in   complex,    twin  crystals,  resembling 
tetragonal  pyramids. 


Contain  little  or  no  aluminium .— 
After  dissolving  in  HC1  and 
separating  the  silica  (p.  108, 


8  1)  the  solution  gives  no,  or 

only  a  slight,  precipitate  with  Fusible  to  a  blebby 


ammonia. 


Usually  found  in  simple  prismatic  crystals  with 
oblique  terminations. 


Gives  a  poor  jelly  with  HC1.     B.  B.  fuses  to  a 
clear  glass.     


Laumontite. 


Gismondite. 


Pectolite. 


Okenite. 


Gyrolite. 


C   METALLIC   LUSTER.  278 

,  or  only  Slowly  or  Partially  Volatile. 

bule,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

nd  yield  gelatinous  silica  upon  evaporation. 

he  finely  powdered  material  in  a  test-tube  with  from  3-5  c.c.  of  hydrochloric  acid,  and  boil  until  not 
i  the  volume  becomes  small  the  contents  of  the  tube  should  thicken,  owing  to  the  separation  of 
,ed  with  additional  water  or  acid. 

lontainiug  water  of  crystallization  or  the  hydroxyl  radical. 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 

ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

Mouocl. 
U.  cryst. 

Ca(B.OH)Si04. 

^yeSow:™'-- 

F.  Uneven. 

5-5.5 

2.9-3.0 

2-2.5 

BaAl(A1.2OH) 
(Si03)3.2H20. 

Colorless, 
white,  pink. 

Vitreous. 

C.  Prism.,  per. 
F.  Uneven. 

4-4.5 

2.77 

2.5 

Orthorh. 
C1.27,  p.  219. 

Mu,(AlO)a(8iO»)8. 
6H2O. 

Brown. 

Vitreous. 

C.  Basal,  per. 

4-4.5 

2.84 

3 

Monocl. 
Foliated. 

(Zn.OH)2SiO8. 

White,      pale- 
green,  or  blue. 

Vitreous. 

C.  Prism.  ,  per. 
F.  Uneven. 

4.5-5 

3.45 

5 

Orthorh. 
Page  207. 

H2CaZnSiO6. 

Amethystine 
to  white. 

Vitreous. 

C.  Pinac.,  per. 
F.  Uneven. 

5-6 

3.33 

4 

Monocl. 

C1.30,p.^l9. 

H6(Naa,Ca)4 
(Al.NaCOs)aAl« 
(SiO*),,. 

Yellow,  pink, 
gray,  white. 

Vitreous, 
greasy. 

D.  Prismatic. 
F.  Uneven. 

5-6 

2.4-2.5 

2.5-3 

Hexag. 
U.  mass. 

Uncertain. 
Si,Y,Ca,0,C02,H20 

Yellowish- 
brown. 

Greasy. 

C.  Pinacoidal. 

5-5.5 

3.41 

5? 

Orthorh. 

Na2Al(AlO)(SiO,)3. 
2H20. 

Colorless  or 
white. 

Vitreous. 

3.  Prism.,  per. 
F.  Uneven. 

5-5.5 

2.25 

2.5 

Orthorh. 
Prismatic 

HNaaAl3(SiO4)3. 
3H20. 

White  to  dark- 
gray. 

Vitreous. 

4.5-6 

2.3-2.5 

2-3 

Hexag. 

H2Mg5(SiO3)6. 
3H20. 

Flesh-red. 

Pearly, 
greasy. 

F.  Splintery. 

2.5 

4? 

Massive. 

CaAl(Al.SOH) 

(SiO3)3.2H2O. 

Colorless  or 
white. 

Vitreous. 

C.  Prismatic. 

5-5.5 

2.16-2.4 

2.5 

Monocl. 
Prismatic. 

Approx.  NaaCa2Ale 

Si9O3o.8HaO 

White,     gray, 
yellow. 

Vitreous, 
silky. 

C.  Prism,,  per. 

5 

2.2-2.4 

2-2.5 

Monocl. 
Column. 

(Ca,Na3)Ala(SiO4)8. 
2|H20. 

Colorless, 
white,  gray. 

Vitreous,           C.  Piuac.,  per. 
pearly.  F.  Uneven. 

5-5.5 

2.8-2.4 

2-2.5 

Orthorh. 
Hex.  Rh. 

CaAl(A1.2OH) 

(SiO3)3.4H2O. 

White,     gray, 
red. 

Vitreous. 

F.  Uneven. 

4-4.5 

2.0-2.16 

2-2.5 

Ca(A1.20H)a 

(Si2O6)2.2H2O. 

White,  gray.    |Vi~  ^ 

C.Pinacoidal& 
prismatic,  per. 

3.5-4 

2.25- 
2.35 

2.5 

Monocl. 
Prismatic 

(Ca,K2)Al2(SiO3)4. 
4H2O? 

Colorless  or 
white. 

Vitreous. 

F.  Uneven. 

4.5 

2.26 

3 

Monocl. 
Twinned. 
Monocl. 
Fi.jr.  361. 
Fibrous. 
Compact. 

HNaCa2(SiO3)3. 

Colorless, 
white,  gray. 

Vitreous,            C.  Pinac.,  per. 
pearly.  F.  Splintery. 

5 

2.7-2.8 

2.5-3 

H2Ca(SiO3)2.H2O. 

White,  cream, 
bluish-white. 

Dull,  pearly.     F.  Splintery. 

4.5-5 

2.28 

2.5 

PI2Caa(SiO3)3.H2O. 

White. 

Vitreous, 
pearly. 

3-4 

3 

Radiated. 

(Page  279.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

B. — Fusible  from  1-5,  and  Non-volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  glob- 
ule, and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

DIVISION  3. — Soluble  in  hydrochloric  acid,  and  yield  gelatinous  silica  upon  evaporation 
Section  b. — In  the  closed  tube  give  little  or  no  water. — In  part. 


279 


II.   MINERALS   W1THO 
B.— Fusible  from  1—5,  and  Non-volat 

PABT  III.— With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  < 

DIVISION  3.— Soluble  in  hydrochloric  acid,  ai 
Section  b.—ln  the  closed  tube  give  little  or  no  water.— Art 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

Contain  the  sulphide  radical.— 
Dissolve    in  HC1  with   slight 
evolution  of  hydrogen  sulphide, 
which  may  be  detected  by  its 
disagreeable  odor. 

Imparts  to  the  borax  bead  in  O.  F.  a  reddish- 
violet  color  (manganese}.  $0°  Compare  Dana- 
lite,  pp.  269  and  294. 

Helvite. 

B.  B.  gives  !in  intense  yellow  flame  (sodium). 
Reacts  for  a  sulphate  (p.  122,  §  1). 

.azurite. 
(Lapis-  Lazuli.) 

Contain     chlorine.—  The    HNO3 
solution     gives     with     silver 
nitrate  a   precipitate  of  silver 
chloride. 
B.  B.  color  the  blowpipe  name 
intensely  yellow  (sodium). 

Fuses  to  an  opaque,  greenish  bead.  The  HC1 
solution  gives  with  turmeric-paper  the  zir- 
conium reaction  (p.  133). 

Eudialyte. 
(Eucolite.) 

The  dilute  HC1  solution  gives  a  precipitate  with 
barium  chloride  (sulphate,  p.  122,  §  1). 

Microsommite. 

Does  not  give  the  foregoing  reaction  for  a  sul 
phate.  Fuses  to  a  colorless  glass. 

Sodalite. 

Contain  the  sulphate  radical.  — 
The  dilute  HC1  solution  gives 
a  precipitate  with  barium  chlo- 
ride (p.  122,  §1). 

Haiiyuite  is  distinguished  from  Noselite  by  con 
taining  considerable  calcium.     Test  as  directed 
on  p.  110,  §4. 

laiiynite. 
(Haiiyne.) 

Noselite. 
(Nosean.) 

Contain  boron.  —  Give  the  boron 

Swells,   and  fuses  with  difficulty    to    a    whit 
enamel. 

Cappelenite. 

reaction  with    turmeric-paper 
(p.  56,  §  2). 

Intumesces  and  fuses  to  a  black  glass. 

Horn  i  lite. 

Contain  manganese.—  Impart  tc 

The  fine  powder  when  fused  on  charcoal  wit 
a  little  Na2CO3  gives  a  coating  of  oxide  of  zinc 

TROOSTITE.     Se 
willemite,  p.  294 

the    borax    bead    in  O.    F.  n 
reddish-violet  color. 

Contains  little  or  no  zinc. 

Tephroite. 

DIVISION  3,  Section  b.—  Concluded  on  next  page 


?   METALLIC   LUSTER. 

,  or  only  Slowly  or  Partially  Volatile, 

mle,  and  when  fused  alone  in  the  reducing  flame  do  not  "become  magnetic. 

ield  gelatinous  silica  upon  evaporation. 

*rous  silicates,  or  those  containing  only  a  little  hydroxyl. 


279 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

l5(R2S)(SiO4),. 

I  =  Be,  Mn  &  Fe. 

Yellow, 
brown,  green, 
red. 

Vitreous, 
resinous. 

F.  Uneven. 

6-6.5 

3.2-3.35 

4-4.5 

Isom.  Tet. 

Naa,Ca),(Al.NaS.) 
Al2(SiO4)3. 

Al.NaSOJ  is...  w. 
(Al.NaSa). 

Deep  azure- 
blue,  green- 
ish-blue. 

Vitreous. 

F.  Uneven. 

5-5.5 

2.4-2.45 

3.5 

Isometric. 
U.  mass. 

Jncertain. 
Ji,Zr,Na,Ca,Fe", 

Ce,Mn.Cl,(OH). 

Rose-  to 
brownish- 
red,  brown. 

Vitreous. 

C.  Basal,  per. 
F.  Splintery. 

5-5.5 

2.9-3.0 

3 

Hex.  Rh. 

Jn  certain. 
ii,Al,Ca,Na,K.O,Cl. 
(S04),(CO,). 

Colorless, 
white. 

Vitreous. 

C.  Prism.,  per. 
F.  Uneven. 

6 

2.45-2.5 

3.5 

Hexag. 
Prismatic. 

Na4(AlCl) 
Al2(SiO4)3. 

White,  gray, 
blue,  green. 

Vitreous, 
greasy. 

C.  Dodecahed. 
F.  Conchoidal. 

5.5-6 

2.15-2.3 

3.5-4 

Isometric. 

.Ca,Naa)a 

(Al.NaSO4)Ala 
(SiO4)s. 

Blue,  green, 
yellow,  white. 

Vitreous. 

C.  Dodecahed. 
F.  Uneven. 

5.5-6 

2.4-2.5 

4-4.5 

Isometric. 

Na4(Al.NaSO4)Al, 
(SiO4)3. 

Gruy,  green, 
blue,  brown. 

Vitreous. 

F.  Uneven. 

5.5 

2.  25-2.4 

3.5-4 

Isometric. 

BaY6B6Si3O25. 

Greenish- 
brown. 

Vitreous, 
greasy. 

F.  Conchoidal. 

6-6.5 

4.41 

4-5 

Hexag. 

(Ca,Fe)3(BO)a 

(Si04)2. 

Brownish- 
black  to  black. 

Resinous, 
vitreous. 

F.  Uneven. 

5 

3.38 

2 

Monocl. 

(Zn,Mn)2SiO4. 

Apple-green, 
flesh-red, 
brown. 

Vitreous. 

C.  Basal  & 
prismatic. 
F.  Uneven. 

5.5 

4.18- 

4.5-5 

Hex.  Rh. 
Page  196. 

Mu2SiO4. 
Mg,  Fe,  Ca,  &  Zn  iso. 
w.  Mn. 

Smoky-  gray, 
brownish-red. 

Vitreous, 
greasy. 

C.  Pinacoidal. 
F.  Uneven. 

5.5-6 

4-4.12 

3-3.5 

Orthorh. 
U.  mass. 

(Page  280.) 

II.  MINERALS   WITHOUT  METALLIC   LUSTER. 

B.— Fusible  from  1-5,  and  Non-volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  glob 
ule,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

DIVISION  3.— Soluble  in  hydrochloric  acid,  and  yield  gelatinous  silica  upon  evaporation. 
Section  b. — In  the  closed  tube  give  little  or  no  water. — Concluded 


28U 


II.   MINERALS  WIT: 
B.— Fusible  from  1—5,  and  Non-volat 

PART  III.— With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  g 

DIVISION  3.— Soluble  in  hydrochloric  acid, 
Section  b.—In  the  closed  tube  g\ 


General  Characters. 


Contain  titanium.— The  HC1  so- 
lution when  boiled  with  tir 
assumes  a  violet  color. 


Contains  niobium. — The  HC1  so 
lution   when    boiled   with  tin  The 
assumes  a  blue  color  (p.  99 


Contains  zirconium.— Gives  the 
zirconium  reaction  with  tur 
meric-paper  (p.  133). 


Contains    the    Tare-earth    meta 
yttrium  (p.  65). 


Specific  Characters. 


Name  of  Species. 


uses  quietly. 


Compare  Andradite  (p.  269).    (Meianite.) 


'use  with  intumescence.  After  separation  of 
the  silica,  the  reactions  for  the  rare-earth  metals 
may  be  obtained  (p.  65). 


uc  HC1   solution  imparts  an  orange  color  to 
turmeric- paper  (zirconium,  p.  133). 


Wohlerite. 


Fuses  to  a  yellowish-white  enamel. 
Ut^P  Compare  Eudialyte  (p.  279). 


Hiortdahlite. 


B.  B.  swells,  cracks  apart,  and  often  glows. 


Contain  aluminium  and  in  som 
cases  also  calcium,  but  do  nc 
give  the  reactions  of  the  fore 
going  divisions.— In  the  HC 
solution,  after  separation  of  the, 
silica  (p.  108,  §1),  ammonia 
produces  a  precipitate  of  alu- 
minium hydroxide  (p.  42,  §2) 
When  calcium  is  present  it 
may  be  precipitated  in  the  fil- 
trate from  the  aluminium  by 


Very  easily  soluble  in  HC1. 
yellow  flame  (sodium). 


B.  B.  gives  a  strong 


Rather  difficultly  soluble  in  HC1.     Gives  littl 
color  to  the  blowpipe  flame. 

ompare  The  Feldspars  (p.  285).    


Fuses  to  a  white  enamel. 


Fuses  with  slight  intumescence  to  a  greenish  c 
yellowish  glass. 


means  of   ammonium 
(p.  60,  §  6). 


oxalate 


Fuses  with  intumescence  to  a  dark  slag.     Give 
reactions  for  the  rare-earth  metals  (p.  65). 


Oives  a  reaction  for  magnesium 
ufter  the  separation  of  silica 
and  calcium  (p.  91,  §1,  6). 


Fuses  with  difficulty  to  a  grayish  mass. 


Difficultly  fusible. 


scheffkinite. 


inkite. 


Gadolinite. 


NEPHELITE. 

(Nepheline,    E18E 
lite.) 


NORTHITE. 

(Lime  Feldspar.) 


Sarcolite. 


Melilite. 


Allanite. 


Gehlenite. 


Monticellite. 


UT   METALLIC   LUSTER. 
,  or  only  Slowly  or  Partially  Volatile. 
ule,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

yield  gelatinous  silica  upon  evaporation. 
itlle  or  no  water. — Concluded. 


280 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

a3(Fe,Ti,Al)2 
[(SifTi)04]i. 

Black. 

Vitreous. 

F.  Uneven. 

7-7.5 

3.88 

4 

Isometric. 

'n  certain. 
i,Ti,Th,Ce,Fe, 
Ca,O. 

Velvet-black. 

Vitreous. 

F.  Uneven. 

5-5.5 

4.55 

4 

Massive. 

ra9CailCe3(TiF2)4 
(SiO4),«. 

Yellowish- 
brown,  straw- 
yellow. 

Vitreous, 
greasy. 

C.  Piuacoidal. 

5 

3.46 

Monocl. 

ncertain. 
,i,Zr,Nb,Ca,Na,0. 

Light  yellow 
to  brown. 

Vitreous, 
resinous. 

C.  Pinacoidal. 
F.  Conchoidal. 

5.5-6 

3.44 

3-3.5 

Monocl. 

Na2,Ca)(Si,Zr)O3? 

Straw-yellow, 
yellowish- 
brown. 

Vitreous, 
greasy. 

F.  Uneven. 

5.5-6 

3.26 

3? 

Triclinic. 

^eBe9YaSia010. 

Greenish-  to 
brownish- 
bluck. 

Vitreous, 
greasy. 

F.  Conchoidal, 
splintery. 

6.5-7 

4.2-4.5 

5 

Monocl. 

Na2,Ka,Ca)4 
Al*Si9034. 
..pprox.  NaAlSiO4. 

Colorless, 
gray,  greenish, 
reddish. 

Vitreous, 
greasy. 

C.  Prismatic. 
F.  Uneven. 

5.5-0 

2.55- 
2.65 

4 

Hexag. 
Class  11, 
Page  219. 

:nAla(SiO4)2. 

Colorless, 
white,  gray. 

Vitreous. 

C.  Basal,  per.  & 
pinacoidal. 
F.  Uneven. 

6-6.5 

2.75 

4.5 

Triclinic. 

Ca,Na),Ala(Si04)«. 

Flesh-  to  rose- 
red,  white. 

Vitreous. 

F.  Conchoidal. 

6 

2.5-2.9 

2.5-3? 

Tetrag. 

01.  20,p.  219. 
Tetrag. 

Jucertaiu. 
>i,Al,Fe,Ca,Mg, 
Na,0. 

Green,  yellow, 
brown,  white. 

Vitreous, 
resinous. 

C.  Basal. 
F.  Uneven. 

5 

2.9-3.1 

4 

ra(R'".OH) 

R'"2(SiO4)3. 
I"  =Ca  &  Fe. 
l"'=Al,Fe,Ce,La,&Di. 

Brown  to 
pitch-black. 

Resinous, 
vitreous. 

F.  Uneven  to 
Conchoidal. 

5.5-6 

3.5-4.2 

2.5 

Monocl. 
U.  mass 

Ca,Mf?,Fe)s 

Al2Si2O,0. 

Grayish-green 
to  brown. 

Vitreous, 
resinous. 

F.  Uneven. 

5.5-6 

2.9-3.0 

4.5-5 

Tetrag. 

}aMgSiO4. 

Fe  iso.  w.  Mg. 

Colorless,  to 
pale  yellow 
or  green. 

Vitreous. 

C.  Pinacoidal. 
F.  Uneven. 

5-5.5 

3.1 

5 

Orthorh. 

(Page  281.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

B.— Fusible  from  1-5,  and  Non- volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  glob- 
ule, and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

DIVISION  4. — Decomposed  by  hydrochloric  acid  with  the  separation  of  silica,  but  without 

the  formation  of  a  jelly. 

Section  a. — In  the  closed  tube  give  water. — In  part. 


28!  II.   MINERALS  WITHC 

B.— Fusible  from  1—5,  and  Non-volata 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  g\ 
DIVISION  4. — Decomposed  by  hydrochloric  acid  with  tf 

In  order  to  determine  that  a  mineral  belongs  in  this  division  treat  one  or  two  ivory-spoonfuls  c 
less  than  1  cc.  of  acid  remains.  The  behavior  during  this  treatment  shoukl  be  carefully  observed. 
to  the  fine,  suspended  material;  when  boiled,  however,  the  liquid  becomes  translucent,  although  U 
decide  from  appearances  whether  the  insoluble  material  is  separated  silica  or  the  undecomposed  mil 
to  oxidize  any  iron  that  may  be  present,  dilute  with  5  cc.  of  water,  boil,  and  filter,  when,  if  decoo 
will  precipitate  aluminium  and  iron  which  may  be  filtered  off.  In  the  strongly  ammoniacal  filtrat 
while  if  other  bases  are  present  (sodium,  potassium  and  lithium  excepted)  one  or  the  other  of  the 
for  testing  for  the  bases  see  p.  110,  §  4.  There  are  some  minerals  which  are  slowly  attacked  by  acid* 
carbonate  and  sodium  phospate;  the  minerals  in  this  division,  however,  are  readily  decomposed  by  i 

Section  a. — In  the  closed  tube  give  water. — Silicates  co 


General  Characters. 


Specific  Characters. 


Name  of  Species. 


Structure  micaceous.  Exfoliates  prodigiously  when  heated  B.  B.  Under  the  name 
Vermiculite  a  number  of  silicates  of  aluminium  and  magnesium  are  included 
which  have  resulted  generally  from  the  decomposition  or  alteration  of  different 
kinds  of  mica.  Their  composition  cannot  be  expressed  by  simple  formulas. 
See  The  Micas  (p.  284). 


Vermiculite. 

(Jefferisite.) 


Fuses  quietly  to  a  white  enamel.     The  HC1  solution  colors  turmeric-paper  orange- 
yellow  (zirconium,  p.  133). 

Catapleiite. 

Puses  with  slight  intumescence  to  a  brown  glass.     The  water  in  the  closed  tube 
gives  an  acid  reaction  with  test-paper  (fluorine}.     Gives  reactions  for  the  rare- 
earth  metals  (p.  65*. 

Mosandrite. 

Difficultly   fusible.       The    HC1 
solution,  if  sufficiently  dilute, 
gives  no  or  only  a  slight  pre- 
cipitate with  ammonia  and  am- 
monium carbonate,  but  gives 
an   abundant  precipitate  with 
sodium  phosphate  (magnesium, 
p.  91,  §  1,  b). 

Compact,  with  fine  earthy  texture. 

Sepiolite. 
(Meerschaum.) 

Somewhat  resembles  a  gum. 

Deweylite. 

(Gyrnnite.) 

Commonly  in  compact,  greenish  masses.     Some- 
times fibrous  (Chrysotile,  Fig.  3CO,  p.  221)  or 
foliated  (Marmolite). 

SERPENTINE. 

(Chrysotile,       S* 
pentine'-  asbesti 
Marmolite.) 

Gives   a  reaction    for  chlorine   when   tested    as 
directed  on  p.  68,  §  3. 

Friedelite. 

the  borax  bead  in  O.  F.  a  red- 
dish-violet color. 

Fuses  quietly  to  a  black  glass. 

iiementite. 

Splits    apart    and     often    crumbles    when    first 
heated  B.  B. 

Inesite. 

DIVISION  4.  Section  a.— Concluded  on  next  page. 


METALLIC   LUSTER. 


281 


>r  only  Slowly  or  Partially  Volatile. 

e,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic, 
wation  of  silica,  but  without  the  formation  of  a  jelly. 

finely  powdered  material  in  a  test-tube  with  from  3  to  5  cc.  of  hydrochloric  acid,  and  boil  until 
en  the  powder  is  first  shaken  up  with  the  cold  acid  the  liquid  will  generally  appear  milky,  owing 
mrated  silica  prevents  it  from  becoming  perfectly  clear.  After  a  little  experience  one  can  usually 
in  order  to  decide  definitely,  however,  proceed  as  follows  :  Add  a  drop  of  nitric  acid  in  order 
ion  has  taken  place,  the  bases  will  be  in  the  filtrate.  Ammonia,  added  in  excess  to  the  solution, 
monium  carbonate  and  sodium  phosphate  will  precipitate  calcium  and  magnesium,  respectively, 
ents  previously  mentioned  will  be  very  sure  to  produce  a  precipitate.  For  more  complete  details 
give,  consequently,  slight  precipitates  of  the  bases  when  tests  are  made  with  ammonia,  ammonium 


ng  water  of  crystallization  or  the  hydroxyl  radical. 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

icertain. 
,Al,Mg,O,(HaO). 

I'e  iso.  w.  Al  &  Mg. 

Yellow, 
brown,  light 
to  dark  green. 

Pearly. 

C.  Basal,  per. 

1-1.5 

2.2-2.3 

4-4.5 

Mouocl.  ? 
Mica- 
ceous, 
foliated. 

4(Na3,Ca)ZrSi8Oii 

Yellow,  brown, 
gray,  violet. 

Vitreous. 

C.  prism.,  per. 
F.  Conchoidal. 

6 

6.28 

2.5    jHexng. 

iaNa2CaioCe2 
[(Ti,Zr)(OH.F)2]4 
(Si04),a, 

Reddish-  to 
green  ish- 
brown. 

Greasy, 
resinous. 

C.  One  direc- 
tion. 

4 

2.9-3.0 

2.5-3 

Monocl.  ? 

Compact, 
Earthy. 

Amorph. 

«MgaSisOJ0. 

White  to 
grayish-  white. 

Dull. 

F.  Uneven. 

2-2.5 

20 

5 

4Mg4(Si04)3.4HaO 

iso.  w.  Mg. 

Yellow,  brown, 
apple-green 

Resinous. 

F.  Uneven, 
conchoidal. 

3-4 

2.40 

4-5 

4(Mg,Fe)sSi»OB. 

Olive-  to  black- 
ish-green, yel- 
lowish green, 
white. 

Greasy, 
wax-like. 

F.  Uneven, 
splintery. 

2.5-5 
U.  4 

2.5-2.65 

5-5.5 

Massive 
Pseud  o- 
morphous 
(p.  2-JO.. 

7(MuCl)Mn4 
(Si04)4. 

Rose-  red. 

Vitreous. 

C.  Basal,  per. 

4-5 

3.07 

4 

Hexag. 

2MnSiO4? 
?,  Mg,  &Zn  iso.w.Mn 

Pale  grayish- 
v  el  low. 

Pearly. 

C.  Basal,  per. 

2.5-3 

2.98 

3.5 

Folialed. 

Mu,(Ja»C3l(Js. 
2HaO. 

Rose-  to  flesh- 
red. 

Vitreous. 

'J.  Pinac.,  per. 
F.  Uneven. 

6 

3.03 

3 

Triclinic. 

(Page  282.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

B.— Fusible  from  1-5,  and  Non-volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  glob- 
ule, and  when  fused  alone  in  the  reducing  flame  do  not  'become  magnetic. 

DIVISION  4. — Decomposed  by  hydrochloric  acid  with  the  separation  of  silica,  but  without 

the  formation  of  a  jelly. 

Section  a, — In  tlie  closed  tube  give  water. — Concluded. 


282 


II.   MINERALS   WITHOUr 
B.— Fusible  from  1—5,  and  Non-volatile, 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  gl 
DIVISION  4. — Decomposed  by  hydrochloric  acid  with  th< 

Section  a. — In  the  closed  t\ 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

Contain     calcium,    but    no    alu- 
minium. —  After   decomposing 
with  HC1  and  separation  of  the 
silica,  ammonia  produces  little 
or  no  precipitate,  but  ammo- 
nium    carbonate     precipitates 
calcium  carbonate  (p.  60,  §  5). 

Fuses  quietly  to  a  glass  coloring  the  flame  yellow 
(sodium).  3%  H2O. 

Pectolite. 

Fuses  with  swelling  to  a  white,  vesicular  enamel. 
Colors  the  flame  pale  violet  (potassium). 
We  HaO. 

APOPHYLLITE. 

B.   B.  at   first    becomes   opaque 
and  then  fuses  quietly  to  a  clear 
glass.    Colors  the  flame  yellow. 

Usually  crystallizes  in  trapezohedrons  (Fig.  105, 
p.  171),  sometimes  in  combination  with  the 
cube  (Fig.  107). 

ANALCITE. 

Gives  little  water  in  the  closed 
tube.   Fuses  with  intumescence 
to  a  swollen,  blebby  enamel. 

Decomposed  slowly  and  with  difficulty  by  HC1. 

PREHNITE. 

Give  much  water  in  the  closed 
tube.      Generally     fuse    with 
swelling  and  intumescence  — 
After  decomposing  with  HC1 
and   separation   of   the   silica, 
ammonia  produces   a  precipi- 
tate of    aluminium  hydroxide, 
and  in  the  filtrate  ammonium 
carbonate  gives  a   precipitate 
of  calcium,    barium  or  stron- 
tium carbonates. 
Many  of  these  silicates  are  closely 
related    in  chemical  composi- 
tion, and  differences  in  crystal- 
lization  must   be  relie  1  upon 
for  their  identification.     Har- 
motome,   Wellsite,   and    Phil- 
lipsite  generally  occur  in  com- 
plex, twin   crystals,  often  re- 
sembling    tetragonal    prisms, 
terminated  by  pyramids  of  the 
opposite  order. 

Contain  barium.  —  The  dilute  HC1  solution  gives 
with  dilute  H2SO4  a  precipitate  of  barium  sul 
phate.  B.  B.  Brewsterite  exfoliates  prodigiously 
before  fusing;  Wellsite  and  Harmotome  whiten 
and  then  fuse. 

Brewsterite. 

Wellsite. 

Harmotome. 

Hexagonal,  rhombohedral.  B.B.  fuse  with  swell- 
ing. Gmelenite  often  cracks  and  splits  apart 
before  fusion. 

CHABAZITE. 

(Phacolite.) 

jimelenite. 

Fuse  with  swelling  and  intumescence. 
Stilbite  is  commonly  in  sheaf-like  aggregations 
of    crystals,     or    radiated  ;    isolated    crystals, 
owing    to  twinning,    have  an   orthorhombic 
aspect.    On  Heulandite  the  piuacoid  faces  with 
pearly  luster  are  usually  lozenge-shaped. 

STILBITE. 

(Desmine.) 

HEULANrilTE. 

Spistilbite. 

B.  B.  Whitens  and  fuses  without  swelling  to  a 
vesicular  enamel.  Reacts  for  potassium  (p.  105, 

§!•_£); 

Phillipsite. 

Crystallizes  in  octahedrons. 

Faujasite. 

IETALLIC   LUSTER, 
only  Slowly  or  Partially  Volatile. 

le,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic, 
aration  of  silica,  but  without  the  formation  of  a  jelly. 
ive  water. — Concluded. 


382 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi 
bility. 

Crystalli- 
zation. 

Monocl. 
Fig.  361, 
page  222. 

Tetrag. 
Page  181. 

Isometric. 

fciCaa(SiO,)s. 

Colorless, 
white,  gray. 

Vitreous, 
pearly. 

C.  Piuac.,  per. 
F.  Splintery. 

5 

2.7-2.8 

2.5-3 

KCa4(SiO3)8. 
4^H20. 

I4)  &  F  in  traces. 

White,   pale- 
green,  yel- 
low, rose. 

Pearly, 
vitreous. 

C.  Basal,  per. 
F.  Uneven. 

4.5-5 

2.3-2.4 

2 

,Al(SiO3)2.HaO. 

Colorless  or 
white. 

Vitreous. 

F.  Uneven. 

5-5.5 

2.27 

3.5 

Ca.Al,(Si04)>. 
iso.  w.  Al. 

Apple-green, 
gray,  white. 

Vitreous. 

F.  Uneven. 

6-6.5 

2.90 

2.5 
3 

Orthorh. 
lie  inform. 

(tir,Ba,Ca)Al2 
(SiO3)6.3H2O. 

White,  yellow, 
gray. 

Vitreous, 
pearly. 

C.  Piuac.,  per. 
F.  Uneven. 

5 

2.45 

Monocl. 

i,K2,Bn) 
AlaSisO,0.3H2O. 

White  or 

colorless. 

Vitreous. 

F.  Uneven. 

4-4.5 

2.3-2.35 

3 

Monocl. 
Twinned. 
Monocl. 
Twinned. 

a,Ka)AlaSi6O,4. 
5H20. 

White  or 

colorless. 

Vitreous. 

C.  Pinacoidal. 
F.  Uneven. 

4.5 

2.4-2.5 

3 

pros.  (Ca,Naa)Ala 
(Si(V4.6HaO. 

White.yellow, 
flesh  -red. 

Vitreous. 

C.Rhombohed. 
F.  Uneven. 

4-5 

2.05- 
2.15 

3 

Hex.  Rh. 
Page  195. 

prox.  (Na2,Ca)Al2 
(Si03)4.6H20. 

Wiiite,  yellow, 
flesh-red. 

Vitreous. 

C.  Prismatic.    1  A  ~ 
F.  Uneven. 

2.05- 
215 

3 

Hex.  Rh. 

(Ca,Na2)Al2 
(SiO3)6.4H2O. 

White,  yellow, 
brown,  red. 

Pearly, 
vitreous. 

C.  Pinac.  ,  per. 
F.  Uneven. 

3.5-4 

2.1-2.2 

3 

Monocl. 
Twinned. 

Monocl. 

Monocl. 
Twinned. 

Monocl. 
Twinned. 

(Ca,Xa2)Al2 
(SiO3)6.3H2O. 

White,  yellow, 
red. 

Pearly, 
vitreous. 

C.  Pinac.  t  per. 
F.  Uneven. 

3.5-4 

2.15-2.2 

3 

(Ca,Na2)Al2 
(SiO,),.3HaO. 

White. 

Pearly, 
vitreous. 

C.  Pinac.,  per.  \  A 
F.  Uneven. 

2.2-2.25 

3 

a,Ka,]STa2)Ala 
Si4O12.4H2O. 

White. 

Vitreous. 

C.  Pinacoidal. 
F.  Uneven. 

4.5-5 

2.2 

3 

(Ca,Naa)A1a 
(SiO3)5.9H2O. 

White  to 
brown. 

Vitreous. 

C.  Octahedral. 
F.  Uneven. 

5 

1.92 

3 

Isometric. 

(Page  283.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

B.— Fusible  from  1-5,  and.  Non-volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  ill. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  glob- 
ule, and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

DIVISION  4. — Decomposed  by  hydrochloric  acid,  with  the  separation  of  silica ,  but  without 
the  formation  of  a  jelly. 

Section  b. — In  the  closed  tube  give  little  or  no  water. 
DIVISION  5. — Insoluble  in  hydrochloric  acid,  or  only  slightly  acted  upon. — In  part. 


283 


II.   MINERALS   W1THC 
B. — Fusible  from  1—5,  and  Non-volat: 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  (, 

DIVISION  4. — Decomposed  by  hydrochloric  acid,  with 

Section  b. — In  the  closed  tube  give  littl 


General  Characters. 

Specific  Characters, 

Name  of  Species. 

Insoluble  in  HC1,  and  yet  sufficiently  decomposed  to  give  a  violet  color  (titanium) 
when  the  partial  solution  is  boiled  with  tin  (p.  127,  §  2). 

TITANITE. 

(Sphene.) 

With   borax  in  O.   F.   gives    a 
reddish-violet  bead  (Mn). 

Fuses  with  difficulty  to  a  black  slag.  Crystals 
?ire  apparently  hexagonal. 

Trimerite. 

Fuses  quietly  to  a  white,  almost 
glassy  globule.     Rather  easily 
decomposed  by  HC1. 

After  decomposition  with  HC1  and  separation  of 
the  silica,  ammonia  produces  little  or  DO  pre- 
cipitate. To  detect  calcium,  see  p.  60,  §6. 

WOLLASTONITE. 

Fuses  quietly  to  a  glassy  globule. 
Slowly  acted   upon  by  HC1. 
See  The  Feldspars  (p.  285). 

Usually  shows  striations  on  the  best  cleavage 
surface.  Often  exhibits  a  brilliant  play  of 
colors. 

LABRADORITE. 

(Lime-soda      Fel 
spar.) 

Fuse    with    intumescence    to  a 
vesicular  glass.     Wernerite  is 
slowly  acted  upon  by  HC1. 

Wernerite  gives  during  fusion  a  strong  yellow 
flame  (sodium  chloride};  Meionite  contains  no, 
or  only  a  very  little,  chlorine.  Test  as  directed 
on  p.  67,  §  1. 

WERNERITE. 

(Scapolite.) 

Meionite. 

DIVISION  5. — Not  belonging  to  the  foregoing  divisions.- 

N.B. — The  minerals  in  this  division,  with  the  exception  of  a  few  placed  at  the  beginning,  are  , 
by  treating  the  fused  material  with  nitric  acid  and  evaporating,  as  directed  on  p.  110,  §  4.  There 
often  occur,  namely,  aluminium,  ferric  and  ferrous  iron,  calcium  and  magnesium.  The  flame  tes 
number  of  the  silicates  in  this  division,  after  fusion,  dissolve  in  HC1  and  yield  gelatinous  silica  on  < 
and  treat  the  powder  as  directed  on  p.  278,  Division  3. — A  careful  determination  of  the  crystallizatic 
of  these  silicates,  which,  as  a  rule,  do  not  give  very  pronounced  blowpipe  reactions. 


Phosphates.  —  After    fusion  with 
Na3CO3    and     dissolving     in 
HNO3,  a  little  of  the  solution 
will  give  a  yellow  precipitate 
when    added    to   ammonium 
molybdate  (p.  102,  §  1). 
The  pale  bluish-green  flame  color- 
ation,   often    seen    best    after 
moistening     the    assay    with 
HaSCh,  may  be  employed  for 
the  identification  of    a  phos- 
phate. 

B.  B.  generally  give  a  red  flame  (lithium),  but 
the  color  may  be  obscured  by  sodium.  Give  a 
reaction  for  fluorine  (p.  76,  §  2).  Moutebrasite 
gives  acid  water  in  the  closed  tube  (p.  77,  §5). 

Amblygonite. 

Montebrasite. 

After  fusion  with  Na2CO3  and  dissolving  in 
HC1,  the  solution  gives  a  precipitate  with 
H2SO4  (p.  53,  §  3,  b}. 

Hamlinite. 

Fuse  to  a  white  enamel.  Herderite  gives  strongly 
acid  water  in  the  closed  tube  (p.  77,  §  5). 
Hydro-herderite  and  Cirrolite  give  neutral  or 
only  slightly  acid  water.  To  prove  the  pres- 
ence of  beryllium,  see  p.  54,  §  b. 

Herderite. 

Hydro-herderite. 

Cirrolite. 

Tungstates.  —  Decomposed      by 
boiling  HC1,  leaving  a  yellow 
residue  of    tungstic   oxide  (p. 
128,  §1).     It  is  best  to  treat 
Hubnerite  as  directed  on   p. 
129,  §  2.  Note  the  high  Sp.  Gr. 

Imparts  to  the  borax  bead  in  O.  F.  a  reddish- 
violet  color  (manganese}. 

Hubnerite.     See 
wolframite,  p.  2f 

In  the  dilute  HC1  solution,  made  alkaline  with 
ammonia,  test  for  calcium  with  ammonium 
oxalate  (p.  60,  §  6). 

Scheelite. 

Fluoride.—  Heated  in  a  bulb  tube  with  potassium  bisulphate  give  a  deposit  of 
silica  and  vapors  which  corrode  the  glass  (p.  76,  §  2). 

Sellaitf. 

DIVISION  5. — Continued  on  next  page. 


METALLIC   LUSTER, 
or  only  Slowly  or  Partially  Volatile. 

uh,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic, 
separation  of  silica,  but  without  the  formation  of  a  jelly. 
no  water. — Anhydrous  silicates. 


283 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

aTiSiO6. 

Gray,  brown, 
green,  yellow. 

Resinous, 
adamantine. 

C.  Prismatic. 
F.  Uneven. 

5-5.5 

3.4-3.55 

4 

Monocl. 
Page  213. 

e(Mn,Ca,Fe)SiO4. 

Salmon-pink 
to  colorless. 

Vitreous. 

C.  Basal. 
F.  Uneven. 

6-7 

3.47 

4-5? 

Tricliuic 

aSi03. 

White,  gray, 
colorless. 

Vitreous, 
pearly. 

C.  Pinac.,  per. 
F.  Uneven. 

5-5.5 

2.8-2.9 

4 

Mouocl. 

j  3CaAl2Si2O8. 
JNaAlSi3O8. 

White,  gray, 
brown,  green. 

Vitreous. 

C.  Basal  ,per.  ,& 
piuacoidal 
F.  Uneven. 

5-6 

2.73 

4-4.5 

Triclinic. 
U.  mass. 

Ca4Al«SieO25  . 
Na4Al,8i»O,4Cl. 

White,  gray, 
light-green. 

Vitreous. 

C.  Prismatic. 
F.  Uneven. 

5-6 

2.68 

3 

Tetrag. 
Page  183. 

!a4Al6Si6O26. 

Colorless  to 
white. 

Vitreous. 

C.  Prismatic. 
F.  Uneven. 

5.5-6 

2.74 

4 

Tetrag. 

Cl.20,p.219. 

soluble  in  hydrochloric  acid,  or  only  slightly  acted  upon. 

ties.  This  may  be  proved  by  fusing  with  sodium  carbonate,  and  then  obtaining  gelatinous  silica 
Iso  given  on  pp.  Ill  and  112  some  simple  rnethc  ds  for  the  detection  of  Ihe  buses  \vlii<  h  most 
.  B.,  or  made  as  directed  on  p.  105,  §  1,  c,  serve  for  the  detection  of  sodium  and  potassium. — A 
oration.  To  try  the  experiment  pulverize  some  particles  which  have  been  thoroughly  fused  B.  B., 
eavage,  specific  gravity  and  hardness  will  be  found  most  useful  for  the  identification  and  recognition 


,i(A!F)PO4. 
fa  iso.  w.  Li. 

White  to  pale- 
green  or  blue. 

Vitreous  to 

greasy. 

C.  Ba-al,  per. 
F.  Uneven. 

6 

3.08 

2 

Triclinic. 
U.  mass. 

-i[Al(OH,F)]P04. 
fa  iso.  w.  Li. 

White  to  pale- 
green  or  blue 

Vitreous  to 
greasy. 

C.  Basal,  per. 
F.  Uneven. 

6 

3.00 

2 

Triclinic. 
U.  mass 

3r.OH)(A1.20H)3 
P207. 

5a  iso.w.Sr;F  iso.w.OH 

White  to  yel- 
lowish-white. 

Pearly, 

greasy. 

C.  Basal,  per. 

4.5 

3.15- 
3.25 

4 

Hex.  Rh. 

?a[Be(F,OH)]P04. 

White  to  pale- 
green  or  yellow 

Vitreous, 
resinous 

F.  Uneven. 

5 

3.00 

4 

Monocl. 

XBe.OH)PO4. 

White  to  pale- 
green  or  yellow 

Vitreous, 
resinous. 

F.  Uneven. 

5 

2.95 

4 

Monocl. 

Ca.OH)3Ala(PO4)«. 

White  to  pale- 
yellow. 

Vitreous. 

F.  Uneven. 

5-6 

3.08 

4 

Massive. 

HnW04. 

i'e  iso.  w.  Mn. 

Brown  to 
brown-black. 

Resinous. 

C.  Pinac.,  per. 
F.  Uneven. 

5-5.5 

7.2 

4 

Monocl. 

3aWO4. 

White,  yellow, 
green,  brown. 

Vitreous, 
adamantine. 

C.  Pyramidal. 
F.  Uneven. 

4.5-5 

6.05 

5 

Tetrag. 
Page  182. 

MgF2. 

Colorless  to 
while. 

Vitreous. 

C.  Basal,  per. 
F.  Conchoidal. 

5 

2.95- 
3.10 

4-5? 

Tetrag. 

(Page  284.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

B. — Fusible  from  1-5,  and  Non-volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  glob- 
ule, and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

DIVISION  5.—  Insoluble  in  7iydroc?iloric  acid,  or  only  slightly  acted  upon. — Continued. 


234 


II.   MINERALS   \YITHO 
B.— Fusible  from  1—5,  and  Non-volat 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  g 

DIVISION  5. — Insoluble  in  hydrochloric  aci 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

possess  such  a  remarkable  cleavage  that  they 
as  aggregates  of  minute  scales,  and  then  the 
ly  have  a  hexagonal  and  sometimes  an  ortho- 
ensely  ignited  B.  B.  in  a  closed  glass  tube,  and 
269)  and  Vermiculite  (p.  281). 

Give  a  red  flame  when 
heated  B.  B.  (lith- 
ium). 

Easily  fusible  to  a  white  or  gray  globule.  Gives 
acid  water  when  intensely  ignited  in  a  closed 
tube  (p.  77,  §5). 

LEPI  OOLITE. 

(Lithia  Mica.) 

Easily  fusible  to  a  dark-colored  globule.  See 
p.  270. 

Zinnwaldite. 

B.  B.  exfoliates  prodigiously,  and  fuses  with  dif- 
ficulty. Gives  much  water  in  the  closed  tube. 

Cookeite. 

Scarcely  acted  upon  by 
boiling  concentrated 
H2SO4.—  This    test 
should  be  made  as 
follows;  cleave  out 
a  few  exceedingly 
thin   scales  of   the 
mineral    and    boil 
them  in  a  test-tube 
with  3  c.c.  of  acid 
for  about  a  minute. 
The     mica     scales 
should        preserve 
their      luster     and 
transparency  when 
thus    treated,    and 
the  acid  should  not 
become  turbid  nor 
milky.      Never  at- 
tempt to  add  water, 
or  to  clean  out  the 
test  -  tube  until  the 
acid   (boiling   point 
338°  C.)  has  become 
cold. 

Light-colored  mica.  Found  usually  with  quartz 
and  feldspar. 

MUSCOVITE. 

(Common  or  Potas 
Mica.) 

Imparts  a  green  color  to  the  borax  bead  in  R.  F. 
(chromium). 

Fuchsite. 
(Chrome  Mica.) 

Imparts  a  yellow  color  to  the  blowpipe  flame 
(sodium). 

Paragonite. 
(Soda  Mica.) 

B.  B.  easily  fusible.  Gives  a  faint  violet  flame 
(potassium). 

Alurgite. 

Jlijf 

Soft,  and  has  a  greasy  feel.  Folise  flexible,  but 
not  elastic. 

TALC. 

(Steatite,  Soap- 
stone.) 

THE  MICAS,  and  minerals  with  foliated  structure.*—  These  n 
can  be  split  into  exceedingly  thin  sheets.  Sometimes  thf 
micaceous  structure  is  not  so  apparent.  Distinct  crysta 
rhombic  aspect.  The  true  micas  give  only  a  little  water  v 
their  foliae  are  tough  and  elastic.  &T  Compare  Lepidomt 

Harder  than  the  true  micas.  Folise  rather 
brittle. 

Margarite. 
(Brittle  Mica.) 

&T  Compare  Biotite,  Clinochlore  and  Kammerer- 
ite  below,  which  are  slowly  decomposed  by 
H3SO4. 

Decomposed  by  boiling, 
concentratedHvSOt, 
when  treated  as  di- 
rected in  the  fore- 
going     paragraph, 
that    is,    the    thin 
scales  lose  their  lus- 
ter   and    transpar- 
ency, and  the  acid 
becomes  turbid  or 
milky. 
ET"  Phlogopite       is 
much  more  readily 
decomposed      than 
biotite.      Margarite 
of  the  foregoing  sec- 
tion is  slowly  acted 
upon      by    boiling 
H,S04.    " 

Usually  a  dark-colored  mica.  Found  in  veins 
with  quartz  and  feldspar,  and  very  common  in 
eruptive  rocks. 

BIOTITE.    (Comm< 
dark-green  or  blai 
Mica.) 

Usually  a  light-,  though  sometimes  a  dark-colored, 
mica.  Found  in  crystalline  limestone.  Al- 
most always  contains  about  3  per  cent  of  fluo- 
rine (p.  77,  §  4). 

PHLOGOPITE. 

(Magnesia  Mica.) 

Folia3  flexible,  but  not  elastic.  Give  much  water 
in  the  closed  tube,  but  only  when  intensely 
ignited  B.  B.  Penninite  has  apparently  a  hex- 
agonal-rhombohedral  crystallization  which  re- 
sults from  twinning. 

CLINOCHLORE. 

PENNINITE. 
(Ripidolite,  Chlo- 
rite.) 

Color  reddish.  Imparts  to  the  borax  bead  in 
R.  F.  a  green  color  (chromium).  Otherwise 
like  Clinochlore. 

Kammererite. 
(Chrom  Clino- 
chlore.) 

Gives  with  salt  of  phosphorus  in  O.  F.  a  yellow, 
and  in  R.  F.  a  green,  bead  (vanadium). 

Roscoelite. 

*  It  is  a  difficult  matter  to  pulverize  mic 
cutting  them  up. 

DIVISION  5.— Continued  on  next  page. 


The  material,  however,  may  be  obtained  in  sufficiently  fine  cond 


METALLIC   LUSTER 
or  only  Slowly  or  Partially  Volatile. 

le,  and  when  fused  alone  in  the  reducing  flame  do  not  "become  magnetic. 
only  slightly  acted  upon. — Continued. 


284 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

S[A1(OH,F)2] 
Al(SiO3)3. 

Lilac,  grayish- 
white. 

r*early. 

C.  Basal,  per. 

2.5-4 

2.8-2.9 

2 

Monocl. 
U.  gran. 

,Li)8Fe"(AlO) 
AlF3)AKSi03)8. 

iso.  w.  F. 

Gray,  brown, 
violet. 

Pearly. 

C.  Babul,  per. 

2.5-3 

2.8-3.2 

2.5-3 

Monocl. 

A1.2OH)3(SiO3)a. 

White. 

Dearly. 

C.  Basal,  per. 

2.5 

2.67 

4.5-5 

Mouocl. 
U.  radial. 

KAl,(SiO4)«. 

iso.  w.  Al. 

r'ale-brown, 
-green,  -yel- 
low, white. 

Vitreous, 
pearly. 

C.  Basal,  per. 

2-2.5 

2.86 

4.5-5 

Monocl. 

K(Al,Cr),(Si04),. 

Emerald-green 

Vitreous, 
pearly. 

C.  Basal,  per. 

2-2.5 

2.86 

5 

Monocl. 

iNaAl3(Si04)3. 

Yellowish-  to 
grayish  -white. 

Pearlf 

C.  Basal,  per. 

2.5-3 

2.89 

5 

Monocl. 
U.  gran. 

K,Mg.OH)2 
Al.OH)Al(SiO,)4. 

i  iso.  w.  Al. 

:lose-red  to 
deep-red. 

Pearly. 

C.  Basal,  per. 

3 

2.84 

3 

Monocl. 

,Mg3(SiOa)4. 

Apple-green, 
gray,  white. 

Pearly, 
greasy. 

C.  Basal,  per. 

1 

2.80 

5 

Foliated, 
compact. 

,CaAl4SiaOu. 

Pink,  gray, 
white. 

Pearly. 

C.  Basal,  per. 

3.5-4.5 

3.05 

4-4.5 

Monocl. 

:,H)2(Mg,Fe)2 
(Al,  Fe)2(SiO4), 

Green,  yellow, 
brown,  black. 

Splendent. 

C.  Basal,  per. 

2.5-3 

2.95-3.0 

5 

Monocl. 

I,K)3(Mg,Fe)8 
(Al,Fe)(Si04).. 
iso.  w.  OH. 

Yellowish- 
brown,  green, 
white. 

Vitreous, 
pearly. 

C.  Basal,  per. 

2.5-3 

2.86 

4.5-5 

Monocl. 
Triclinic. 

8Mg6Al2SisO18. 

>  iso.  w.  Mg  &  Al. 

Green  of 
various  shades. 
Rarely  white. 

Vitreous, 
pearly. 

C.  Basal,  per. 

2-2.5 

2.65- 
2.75 

5-5.5 

Monocl. 

8Mg6(Al,Cr)a 
Si,O18 

Garnet-  to 
peach- 
blossom-red. 

Vitreous, 
pearly. 

C.  Basal,  per. 

2-2.5 

2.65- 
2.75 

5-5.5 

Monocl. 

8K2(Mg,Fe) 

(Al.V)4(Si03)13r 

Clove-brown, 
brownish- 

grecn. 

Pearly. 

C.  Basal,  per. 

2? 

2.93 

3? 

Scales. 

for  the  foregoing  tests  by  scraping  with  a  knife-blade,  or  cleaving  into  exceedingly  thin  sheets,  and  breaking  or 


(Page  285.) 

II.  MINERALS   WITHOUT   METALLIC  LUSTER. 

B.— Fusible  from  1-5,  and  Non- volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  glob* 
ule,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

DIVISION  5  — Insoluble  in  hydrochloric  acid,  or  only  slightly  acted  upon. — Continued. 


285 


II.   MINERALS    WITHC 
B.—  Fusible  from  1—5,  and  Non-volati 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  g 

DIVISION  5. — Insoluble  in  hydrochloric  c 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

s-g 

ki 

11 

IJ 

11- 

Contains  barium,  which  may  be  detected  as  described  on  p.  53,  §  3,  6. 

Hyalophane. 
(Barium  Feldspar 

Give  the  reaction  for  potassium  when  mixed  with  gypsum,  and  heated  on 
platinum  wire  (p.  105,  §  1,  c).  Microcline  may  exhibit  on  its  cleavage 
or  crystal  faces  a  system  of  fine  striations,  indicating  a  complex  twinning 
structure,  but  generally  it  is  impossible,  to  distinguish  between  Microcline 
and  Orthoclase  except  by  their  different  action  on  polarized  light.  Sani- 
diue  and  Anorthoclase  are  feldspars  found  in  eruptive  rocks,  which  give 
decided  reactions  for  both  sodium  and  potassium. 

ORTHOCLASE. 

(Potash  Feldspar.; 

MICROCLINE. 

Sanidine. 

ELDSPARS.  —  Characterized  by  two 
ly  90°,  light  color,  difficult  fusibili 
itic  gravity  ranging  from  2.55  to  2.! 

Anorthoclase. 

Give  a  strong  yellow  flame  (sodium),  and  but  little  or  no  reaction  for  potas- 
sium when  mixed  with  gypsum,  and  heated  on  platinum  wire  as  directed 
on  p.  105,  §  1,  c.  —  Generally  on  the  basal  or  best  cleavage  surface  a  sys- 
tem of  fine  parallel  striations  may  be  detected  which  reveal  the  presence 
of  a  complex  twinning  structure  (Fig.  87,  p.  168).  These  minerals,  often 
called  the  Plagioclase  Feldspars,  form  chemically  a  continuous  series 
from  Albite  NaAlSi3O8  to  Auorthite  CaAlaSi3O8.  They  can  scarcely  be 
distinguished  from  oue-another  by  their  blowpipe  reactions,  but  a  test 
for  calcium,  made  as  directed  on  p.  110,  §4,  may  help  in  the  identifica- 
tion. Labradorite  is  very  slowly  acted  upon  by  acids.  Anorthite  dis- 
solves slowly  and  yields  gelatinous  silica  (p.  280). 

ALBITE.      • 

(Soda  Feldspar.) 

OLIGOCLASE. 

(Soda-lime       Felc 
spar.) 

ANDESITE. 

(Lime-soda     Felc 
spar.) 

LABRADORITE. 
(Soda-lime      Felc 
spar.) 

H 

ANORTHITE. 

(Lime  Feldspar.) 

Color  the  blowpipe  flame  green 
(boron).     (R^p  Compare  Bora- 
cite  (p.  277)  which  is  slowly  sol- 
uble in  HC1,  also  Axinite,  below. 

Gives  no  water  in  the  closed  tube. 

Danburite. 

Gives  abundant  water  in  the  closed  tube. 

Howlite. 

"When  mixed  with  potassium  bi- 
sulphate     and     fluorite     and 
heated  on  platinum  wire,  mo- 
mentarily color  the  flame  green 
(boron,  p.  56,  §1). 

B.  B.  fuses  with  swelling  and  bubbling.     May 
impart  a  faint  green  color  to  the  flame. 

Axiniie. 

B.  B.  fuses  with  swelling  and  bubbling,  some- 
times to  a  globule,  sometimes  to  a  slaggy  mass. 
Exhibits  pyroelectricity  (p.  231),  which  suc- 
ceeds best  with  light  colored  varieties. 

TOURMALINE. 

See  p.  300. 

Color   the    blowpipe  flame  red 
(lithium),   which    is    at    times 
obscured  by  sodium  (p.  90). 
ygr  Compare     the     phosphates 
and  micas,  this  division. 

B.  B.  usually  throws  out  fine  branches  when 
first  heated,  and  then  fuses  to  a  clear  glass. 

SPODUMENE. 

(When  green,  Hi< 
denite.) 

Fuses  quietly  to  a  white  enamel. 

Petalite. 

DIVISION  2. — Continued  on  next  page. 


METALLIC   LUSTER. 

% 

or  only  Slowly  or  Partially  Volatile. 

lie,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

or  only  slighly  acted  upon. — Continued. 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

KAlSisOs. 
BaAl2Si2O8 

Colorless, 
white. 

Vitreous. 

C.  Basal,  per., 
pinac.,  z  90°. 

6-6.5 

2.80 

5 

Honocl. 

AJSisOs. 
i  iso.  w.  K. 

Colorless, 
white,  cream, 
flesh  -red,  gray, 
green. 

Vitreous, 
pearly. 

3.  Basal,  per., 
pinac.,  ^  90°. 

6 

2.57 

5 

ktonocl. 
Page  211. 

AlSi3O8. 
i  iso.  w.  K. 

White,  cream, 
red,  green. 

Vitreous, 
pearly. 

C.  Basal,  per., 
pinacoidal, 
/  89°  30' 

6 

2.57 

5 

Triclinic. 

:,Na)AlSisO8. 

Color  lefts, 
white,  gray. 

Vitreous, 
pearly. 

C.  Basal,  per., 
pinac.,  £  90°. 

6 

2.57 

4-4.5 

\Ionocl. 
Triclinic. 

ra,K)A18i3O8. 

Colorless, 
white,  gray. 

Vitreous, 
pearly. 

C.  Basal,  per., 
pinacoidal, 
^  89°-90°. 

6 

2.59 

4-4.5 

aAlSis08. 

Colorless, 
white,  gray. 

Vitreous, 
pearly. 

C.  Basal,  per., 
pinacoidal, 
^  86°  24'. 

6 

2.62 

4-4.5 

Triclhiic, 
Page  216. 

3NaAlSi308. 
lCaAl2Si2O8. 

Colorless, 
white,  gray, 
greenish, 
)luish,  reddish. 
)ften  exhibit 
a  beautiful 
play  of  colors 
on  thepiuacoid 
face  (010). 

Vitreous, 
pearly. 

C.  Basal,  per., 
pinacoidal, 
^  86°  32' 

6 

2.66 

4-4.5 

Triclinic. 
J.  mass. 

INaAlSiaOe. 
!CaAlaSiaO8. 

Vitreous, 
pearly. 

C.  Basal,  per., 
pinacoidal, 
^  86°  14* 

6 

2.69 

4-4.5 

Triclinic. 
J.  mass. 

!NaAlSi308. 
3CaAl3SiaO8. 

Vitreous, 
pearly. 

C.  Basal,  per., 
pinacoidal, 
^  86°  4'. 

6 

2.73 

4-4.5 

Triclinic. 
U.  mass. 

lAl3Si2Oe. 

Colorless, 
white,  gray. 

Vitreous, 
pearly. 

C.  Basal,  per., 
pinacoidal, 
2.  85°  50'. 

6 

2.75 

4.5 

Triclinic. 

iB2(Si04)2. 

White  to  pale 
yellow. 

Vitreous. 

F.  Uneven. 

7 

3.0 

3.5-4 

Orthorh. 

tCa2B6SiO14. 

White. 

Vitreous. 

Splintery. 

3.5 

2.59 

2 

Nodular, 
fibrous. 

,Al4Ba(Si04)5. 

-  Ca,  Mn,Fe,Mg,Zn 
and  a  little  Ha. 

Clove-brown, 
gray,  green, 
yellow. 

Vitreous. 

C.  Pinacoidal. 
F.  Conchoidal. 

6.5-7 

3.27- 
8.35 

2.5-3 

Triclinic. 
Page  218. 

;9Al3(B.OH)2Si4019. 
9  replaced  by 

,  Fe",  Mg,  Mn,  Ca,  Na 
Li&H.    Fiso.w.  OH. 

Black,  brown, 
green,  blue, 
red,  pink, 
white. 

Vitreous. 

F.  Conchoidal, 
Uneven. 

7-7.5 

3.0-3.15 

3-5 
U.S. 

Hex.  Rh. 
Bemimor. 
Page  195. 

,i,Na)Al(SiO,)a. 

White,  gray, 
pink,  emerald 
green. 

Vitreous. 

C.  Prism.,  per. 
F.  Uneven. 

6.5-7 

3.18 

3.5 

Monocl. 
U-  prism. 

,i,Na)Al(SiaO6)a. 

White,  gray, 
pink. 

Vitreous, 
pearly 

C.  Basal,  per. 
F.  Uneven.     * 

6-6.5 

2.40 

4 

Monocl. 
U.  mass. 

(Page  286.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

B.— Fusible  from  1-5V  and  Non-volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  glob' 
ule,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

DIVISION  5. — Insoluble  in  hydrochloric  acid,  or  only  slightly  acted  upon. — Continued. 


286 


II.    MINERALS   WITHO 
B.— Fusible  from  1—5,  and  Non-volati 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  g 

DIVISION  5. — Insoluble  in  hydrochloric  ac 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

Contain  manganese.  —  Impart  to 
the  borax  bead  iu  O.  F.  a  red- 
dish -  violet  color,   which    be- 
comes colorless  in  R.  F. 

Gives  much  water  in  the  closed  tube. 

Carpholite. 

Characterized  by  its  isometric  crystallization. 
Gelutiuizes  with  HC1  after  fusion. 

SPESSARTITE. 

(Manganese  Garnet 

Like  the  foregoing,  but  with  rnonoclinic  crystalli- 
zation. 

Partschinite. 

Distinctly  cleavable  in  two  directions  at  92°-93°. 
Do  not  gelatinize  with  HC1  after  fusion. 
Rhodonite  fuses  to  an  almost  black,  and  Schef- 
ferite  to  a  brownish  glass.  Fowlerite  and  Jef- 
ferson ite  when  fused  on  charcoal  with  a  little 
Na2CO3  in  R.  F.  give  a  slight  coating  of  oxide 
oj  sine. 

RHODONITE. 

Fowlerite. 
(Zinc  Rhodonite.) 

Schefferite.        (Ma: 
ganese  Pyroxene 

Jeffersonite.      (Ma; 
gariese  -  zinc      P. 
roxene.) 

Characterized  by  a  perfect  prismatic  cleavage,  at 
angles  of  55°  and  125°. 

Richterite.         (Ma 
ganese  Amphiboh 

Give  a  reaction  for  vanadium  (p.  130,  §2)  and 
sometimes  for  arsenic  (p.  51,  §  1,  c). 

Ardennite. 

Fuses  with  much  effervescence  to  a  black  glass. 

Piedmontite. 

(  ManganeseEpidott 

Contain    titanium      Fused  with 

Fuse  with  slight  intumescence  to  a  dark  mass. 

TITANITE. 

(Sphene.) 

Na2CO3,  then  dissolved  in  HC1 
and  boiled  with  tin  the  solu- 
tion   becomes  violet  (p.   127, 

§2). 

Guarinite. 

Very  similar  to  Titanite.  Gives  reactions  for 
yttrium  (p.  65). 

Keilhauite. 

Easily  fusible  to  a  black  globule. 

Neptunite. 

Contain  water  of  crystallization. 
—  In  the  closed  tube,  at  a  low 
temperature,  give  much  water. 
A  number  of  the  silicates  beyond 
contain   hydroxyl,  and  on  in- 
tense   ignition    in    the  closed 
tube,  yield  water  (p.  81,  §  1,  &). 
§y  Compare     Prehnite,     Law- 
sonile,     Enclose,      Talc,     and 
others. 

After  boiling  with  HC1  and  filtering,  the  solution 
gives  a  precipitate  with  H2SO4  (barium}.  See 
p.  282. 

Harmotome. 

Fuses  quietly.     Crystallizes  in  six-sided  prisms. 

Offretite. 

Occurs  in  very  fine  capillary  crystals. 

Ptilolite. 

Occurs  in  tabular  crystals  resembling  heulandite, 
and  in  radiated  groups. 

Mordenite. 

DIVISION  5.— Continued  on  next  page. 


METALLIC   LUSTER, 
or  only  Slowly  or  Partially  Volatile. 

ule,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 
or  only  slightly  acted  upon. — Continued. 


286 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

[n(A1.2OH)3 

(SiO,),. 

Straw-yellow, 
wax-yellow. 

Silky. 

F.  Splintery. 

5-5.5 

2.93 

3 

Monocl. 
U.  fibrous 

iln,Fe,Ca)«(AlfFe)a 

(Si04)3. 

Brownish-  to 
garnet-red. 

Vitreous. 

F.  Uneven  to 
Conchoidal. 

7-7.5 

4.2 

3 

Isometric. 
U.  cry  st. 

£n,Fe),Al2(SiO4)3 

Yellowish, 
reddish. 

Greasy. 

F.  Uneven. 

6.5-7 

4.0 

3 

Monocl. 

:nSiO3. 

e  and  Ca  iso.  w.  Mn. 

Rose-red, 
pink,  brown. 

Vitreous. 

C.  Pi  ism.,  per. 
F.  Uneven. 

6-6.5 

3.63 

3-3.5 

Triclinic. 
Page  217. 

ftn,Zn,Fe,Ca,Mg) 
SiO3. 

Rose  -red. 

Vitreous. 

C.  Prism.,  per. 
F.  Uneven. 

6-6.5 

3.67 

3-3.5 

Tricliuic. 
Page  217. 

Ja,Mn)(Mg,Fe) 

(Si08)a. 

Yellowish-  to 
reddish-brown 

Vitreous. 

C.  Prismatic. 
F.  Uneven. 

5-6 

3.5 

4 

Mouocl. 

XMu)(Mg,Fe.Zn) 
(Si03)2. 

Greenish-black 
to  brown. 

Vitreous. 

C.  Prismatic. 
F.  Uneven. 

5-6 

3.6 

4 

Mouocl. 

kIg,Mn,Ca,]S'a2)4 
(SiO,)*. 

Brown,  yellow, 
rose-  red. 

Vitreous. 

C.  Prism.,  per. 
F.  Uneven. 

5.5-6 

3.09 

4 

Monocl. 
Prismatic. 

[5Mn4Al4V.Si4O33? 

s  iso.  w.  V. 

Yellow  to 
yellowish- 
brown. 

Resinous. 

C.  Pinac.,  per. 
F.  Uneven. 

6-7 

3.65 

2-2.5 

Orthorh. 

aa(Al.OH) 

y,Mn,Fi-),(Si04),. 

Reddish- 
brown,  reddish- 
black. 

Vitreous. 

C.  Basal.  ,  per. 
F.  Uneven. 

6.5 

3.5 

3 

Monocl. 

)aTiSi08. 

Gray,  brown, 
green,  yellow, 
black. 

Resinous, 
adamantine. 

C.  Prismatic. 
F.  Uneven. 

5-5.5 

3.4-3.55 

4 

Mouocl. 
Page  213. 

JaTiSiO5. 

Sulphur-  to 
honey-yellow. 

Adamantine. 

C.  Piuacoidal. 
F.  Uneven. 

6 

3.49 

4 

Orthorh. 
Tabular. 

i  CaTiSiO» 

(  (Y,Al,Fe)aSiO.. 

Brownish- 
black. 

Vitreous, 
resinous. 

C.  Prismatic. 
F.  Uneven. 

6.5 

3.5-3.7 

4-4.5 

Monocl. 

Na,K)(Fe,Mn) 
TiSi4O,2 

Black. 

Vitreous. 

C.  Prismatic. 
F.  Uneven. 

5-6 

3.23 

3.5 

Monocl. 

Ba,K,)Al2SiBO14. 
5H20. 

White, 
colorless. 

Vitreous. 

C.  Pinacoidal. 
F.  Uneven. 

4.5 

2.4-2.5 

3 

Monocl. 
Twinned. 

K2,Ca)aAl«Si14O33. 
17H30. 

White, 
colorless. 

Vitreous. 

C.  Prismatr. 

2.13 

3 

Hexag. 
Tabular. 

a,K2,Na,)Al2Si10 
O24.5H3O. 

White. 

Vitreous. 

4-5 

Capillary. 

Ka,Naa,Ca)Al98iio 
034.6|H20. 

White,  yellow, 
pinkish. 

Vitreous, 
pearly. 

C.  Piuac.,  per. 
F.  Uneven. 

3-4 

2.1-2.15 

4-5 

Mouocl. 

(Page  287.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

B.— Fusible  from  1-5,  and  Non-volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  glob- 
ule,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

DIVISION  5. — Insoluble  in  hydrochloric  acid,  or  only  slightly  acted  upon. — Continued. 


28r  II.    MINERALS   WITHC 

B.— Fusible  from  1—5,  and  Non-volat: 
PAR'"  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  g 

DIVISION  5. — Insoluble  in  hydrochloric  at 

The  remaining  silicates  in  this  division  are  arranged  according  to  their  crystallization,  because 
groups.     "VPhen  crystals  are  "Ot  at  hand  the  species  in  almost  all  cases  may  be  identified  readily  bj 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

Fuse  quietly.  Gelatinize  with 
HC1  after  fusiou.  —  To  dis- 
tinguish with  certainty  be 
tween  GrossulariteaudPyrope 
tests  in  the  wet  way  for  calciun 
and  magnesium  must  be  made 

Generally  crystallize  in  dodecahedrons  and  tra- 
pezohedrons  or  their  combination,  Figs.  97, 
105,  and  106  (pp.  170-172). 
BSF*  Compare  the  different  varieties  of  GARNET, 
Almandite  (p.  270),  Andradite  (p.  269),   8pes- 
sartite  (p.  286),  and  Uvarovite  (p.  299). 

GROSSULARITE. 

(Calcium-alumin 
iuni  Garnet.) 

PYROPE. 

(Magnesium-  alu- 
minium Garnet.) 

Fuses  with  intumescence  to  a 
greenish  or  brownish  glass. 

Gelatinizes  with  HC1  after  fusion. 

VESUVIANITE, 

(Idocrase.) 

Fuse  with  intumescence  to  a 
white  mass.  Color  the  flame 
intensely  yellow  (sodium 
chloride). 

Minerals  of  the  SCAPOLITE  GROUP.  Compare 
Meionite  (p.  283).  Wemerite  is  slowly  acted 
upon  by  HC1.  Test  for  chlorine,  after  fusion 
with  Na2CO3,  as  directed  on  p.  67,  §  1. 

WERNERITE. 

(Scapolite.) 

Marialite. 

Fuses  with  intumescence  to  a 
white  blebby  glass. 

B.  B.  in  the  closed  tube  whitens,  and  gives  a 
litfle  water  at  a  high  temperature. 

Milarite. 

B.  B.  whitens,  and  fuses  at  5  to 
5$  to  an  enamel.  Yields  a  little 
water  on  intense  ignition. 

The  varieties  of  beryl  containing  alkalies 
(Na,Li,Cs)are  more  fusible  than  those  without. 
See  p.  300. 

BERYL. 

(Aquamarine  wh< 
pale-green  ;  Em* 
aid     when     dee 
green.) 

Fuses  quietly.  Colors  the  flame 
intensely  yellow  (sodium). 

Generally  phosphoresces  when  heated  (p.  231). 
Gives  a  slight  reaction  for  fluorine  (p.  76,  §  3). 

Leucophanite. 

Fuses  quietly  and  with  difficulty. 

Yields  1^  per  cent  of  water  on  intense  ignition  of 
the  powdered  mineral  in  the  closed  tube. 

IOLITE. 

(Cordierite.) 

Fuses  with  swelling  and  in- 
tumescence to  an  enamel. 

Loses  4.5$  of  water  on  ignition.  Slowly  acted 
upon  by  HCl,  but  gelatinizes  after  fusion. 

PREHNITE. 

B.  B.  cracks  open,  swells,  and 
fuses  to  a  frothy  mass. 

Yields  11  per  cent  of  water  on  intense  ignition  in 
the  closed  tube.  » 

Lawsonite. 

Fuses  with  intumescence,  color- 
ing the  flame  yellow  (sodium). 

Gives  3£  per  cent  of  water  on  intense  ignition  in 
the  closed  tube. 

Epididymite.    See 
eudidymite^  p.  2! 

Very  difficultly  fusible.     Fus.  = 
5-6. 
C3F*  These  minerals  are  the  or- 
thorhombic  representatives  of 
the  Amphibole  and  Pyroxene 
groups,  respectively.  See  p.  288. 

Characterized  by  its  perfect  prismatic  cleavage,  at 
angles  of  54°  and  126°.  Sometimes  fibrous 
(asbestiform). 

Anthophyllite. 

(Asbestus,  in  par 

Has  a  prismatic  cleavage  (less  perfect  than  the 
foregoing)  at  angles  of  88°  and  92°. 

ENSTATITE. 

(Bronzite). 

Fuse  with  swelling  and  in- 
tumescence to  a  slaggy  mass, 
which,  on  continued  heating, 
does  not  readily  melt  to  a  jilob- 
ule.  Gelatinize  with  HC1  after 
fusion. 

Fuse  to  a  light-colored  slag.     Yield  about  2  per 
cent  of  water  on  very  intense  ignition  of  the 
powdered  mineral  in  a  closed  tube. 

ZOISITE. 

Clinozoisite. 

Generally  fuses  to  a  blac  .  slag.     Yields  water 
like  the  foregoing. 

EPIDOTE. 

DIVISION  5. — Concluded  on  next  page. 


METALLIC   LUSTER.  287 

or  only  Slowly  or  Partially  Volatile. 

lie,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

or  only  slightly  acted  upon.— Continued. 

re  are  no  sufficiently  pronounced  blowpipe  characters  -which  may  be  used  for  subdividing  them  into 
ir  blowpipe  and  physical  properties,  as  given  in  the  table. 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

!asAla(SiO4)3. 
e,  Mg,  &  Mn  iso.w.Ca. 
e  iso.  w.  Al. 

Pale-red,  yel- 
low, green, 
white. 

Vitreous. 

F.  Uneven  to 
Conchoidal. 

6.5-7.5 

3.5-3.6 

3 

Isometric. 

VIg,Fe,Ca)3Ala 
(Si04)». 
e  and  Cr  iso.  w.  Al. 

Deep-red, 
rarely  ame- 
thystine. 

Vitreous. 

F.  Uneven  to 
Conchoidal. 

6.5-7.5 

3.6-3.7 

3.5-4 

Isometric. 

!a6[Al(OH,F)] 
(Al,Fe)2(Si04)6. 
g,  Fe  &  Mn  iso.w.  Ca. 

Green,  brown, 
yellow,  blue, 
red. 

Vitreous, 
resinous. 

F.  Uneven. 

6.5 

3.35- 
3.45 

3 

Tetrag. 
Page  180 

Ca4Al6Si6O26. 

Na4Al3Si9O24Cl. 

White,  gray, 
light-green. 

Vitreous. 

C.  Prismatic. 
F.  Uneven. 

5-6 

2.68 

3 

Tetrag. 
Page  183 

ra4Al3Si8O24Cl. 

Colorless, 
white. 

Vitreous. 

5.5-6 

2.56 

3-4 

Tetrag. 
Cl.  20.  p.  219. 

[KCa2Al2(SiaO6)8. 

Colorless  to 
pale-green. 

Vitreous. 

F.  Conchoidal. 

5.5-6 

2.55 

3 

Hexag.  & 

pproximately 
e3Ala(Si03),4H20 
as,  Lia  &  Csa  iso.  w.  Be. 

Green,  blue, 
yellow,  pink, 
colorless. 

Vitreous. 

F.  Conchoidal, 
Uneven. 

7.5-8 

2.75-2.8 

5-5.5 

Hexng. 

Page  188 

ra(BeF)Ca(Si03)a. 

Pale-green, 
yellow,  white. 

Vitreous. 

C.  Basal,  per. 
F.  Couchoidal. 

4 

2.96 

2.5-3 

Orthorh. 
Cl.  27,  p.219. 

[a(Mg,Fe)4A!8 

Si,0Os7. 

Blue,  rarely 
colorless. 

Vitreous. 

C.  Piuacoidal. 
F.  Conchoidal. 

7-7.5 

2.60 

5-5.5 

Orthorh. 

[2Ca2Ala(SiO4)3. 
e  iso.  w.  Al. 

Apple-green, 
gray,  white. 

Vitreous. 

F.Uneven. 

6-6.5 

2.9 

2.5 

Orthorh. 
Ren  iform- 

!a(A1.2OH)(Si08)3. 

Grayish  -blue 
to  white. 

Vitreous. 

C.  Piuac.,  per. 
F.  Uneven. 

8 

3.09 

4 

Orthorh. 

[NaBeSi3O8. 

Colorless. 

Vitreous, 
pearly. 

C.  Basal,  per. 

6 

2.55 

2.5-3 

Orthorh. 

VIg,Fe)SiO3. 
a  iso.  w.  Mg. 

Gray,  clove- 
brown,  green. 

Vitreous, 
pearly. 

C.  Prism.,  per. 

5.5-6 

3.10 

5-6 

Orthorh. 
U.  prism. 

yig,Fe)SiO3. 

Gray  brown, 
green. 

Pearly, 
bronze-like. 

C.  Prismatic. 
F.  Splintery. 

5.5-6.5 

3.2-3.3 

5-6 

Orthorh, 
U.  mass. 

!aa(Al.OH)Ala 
(Si04)3. 

Grayish-white, 
green,  pink. 

Vitreous, 
pearly. 

C.  Pinac.,  per. 
F.  Uneven. 

6-6.5 

3.25- 
3.35 

3-4 

Orthorh. 
U.  prism. 

'u2(Al.OH)A!2 
(Si04)3. 

White  to  pale- 
pink. 

Vitreous. 

C.  Basal,  per. 
F.  Uneven. 

6-7 

3.37 

3-4 

Monocl. 

la^Al.OH) 
(Al,Fe)2(SiO4)3. 

Yellowish-  to 
blackish  - 
green,  gray. 

Vitreous. 

C.  Basal,  per. 
F.  Uneven. 

6-7 

3.37- 
3.45 

3-4 

Monocl. 
Page  213L 

(Page  288.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

B.— Fusible  from  1-5,  and  Non-volatile,  or  only  Slowly  or  Partially 

Volatile. 

PART  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  glob* 
ule,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

DIVISION  5. — Insoluble  in  hydrochloric  acid,  or  only  slightly  acted  upon. — Concluded. 


288 


II.   MINERALS   WITHOU1 
B«— Fusible  from  1—5,  and  Non-volatile 

PABT  III. — With  sodium  carbonate  on  charcoal  do  not  give  a  metallic  g 

DIVISION  5. — Insoluble  in  hydrochloric  ac 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

B.  B.  cracks,  whitens,  and  fuses 
at  5-5£  to  a  white  enamel. 

In  the  closed  tube  at  a  red  heat  unchanged,  but 
on  intense  ignition  B.  B.  whitens  and  yields  6 
per  cent  of  water. 

Euclase. 

Fuse  quietly  or  with  but  little 
intumescence.      Characterized 
by  a  perfect  prismatic  cleavage 
at    angles    of    55°   and    125°, 
which    serves    to    distinguish 
these  minerals  from   those  of 
the  next  section. 
This  section  contains  minerals  of 
the  AMPHIBOLE  GROUP.      The 
crystals  usually  have  a  pris- 
matic habit,  and  are  often  di- 
vergeutor  inradiated-columnar 
aggregates.     Isolated   crystals 
are  usually  bladed  or  six-sided, 
vertically  striated,  and  termi- 
nated by  two  planes  (p.  212). 

Fuses  to  a  colorless  or  nearly  colorless  glass. 
Sometimes  fibrous  (asbestiform). 

TREMOLITE. 

(Asbestus  in  part. 

Fuses  to  a  greenish  or  brownish  globule.  Gives 
but  little  yellow  coloration  to  the  flame. 

ACTINOLITE. 

(Nephrite  or  Jade 
when  compact.) 

Fuses  to  a  dark,  shiny  globule.  Generally  iu- 
tumesces  slightly  and  colors  the  flame  yellow 
(sodium).  The  color  of  the  mineral  deepens  as 
the  amount  of  iron  increases. 

AMPHIBOLE. 
HORNBLENDE. 

Imparts  a  strong  yellow  color  to  the  flame 
(sodium). 

Glaucophane.  See 
riebeckite,  p.  270. 

Fuse   quietly   or   with  little  in- 
tumescence.       The    prismatic 
cleavage,  at  angles  of  87°  and 
93°,  is  not  very   pronounced, 
thus  distinguishing  these  min- 
erals from  those  of  the  fore- 
going group. 
This  section  contains  minerals  of 
the    PYROXENE  GROUP.       The 
crystals    usually    exhibit    the 
combination  of  a  nearly  rect- 
angular prism,  with  truncated 
edges   (p.    211).      They  often 
show  a  distinct  basal  parting 
(p.  225).    The  pyroxenes  have 
a  higher  specific  gravity  than 
the  corresponding  members  of 
the  amphibole  group. 

Fuses  to  a  colorless  or  nearly  colorless  glass. 

DIOPSIDE. 

Fuse  to  a  greenish  or  brownish  glass.  Show 
variations  in  composition  from  Diopside  to 
Hedeubergite,  the  color  deepening  as  the 
amount  of  iron  increases. 

PYROXENE. 

ledenbergite. 

Fuses  to  a  shiny,  black  glass.  Reacts  for  alumin- 
ium &n&  ferric  iron,  p.  110,  §4.  Often  gives 
a  yellow  flame  (sodium).  HSf  Compare  Acmite 
(p.  270). 

AUGITE. 

(Common  pyrox- 
ene of  lavas  and 
igneous  rocks.) 

Fuses  to  a  transparent  blebby  glass,  coloring  the 
flame  yellow  (sodium).  Usually  iu  compact, 
exceedingly  tough  masses. 

Jadeiie. 
(Jade.) 

Fuses  with  intumescence.  Colors 
the  flame  'yellow  (sodium). 

Gives  3£  per  cent  of  water  on  intense  ignition  in 
the  closed  tube. 

Eudidymite. 

Soft,  and  has  a  greasy  feel. 
Difficultly  fusible. 

Gives  4-5  per  cent  of  water  on  intense  ignition 
in  the  closed  tube. 

TALC. 

(Steatite,  Soapston 

Fuses  quietly,  and  without 
marked  flame  coloration. 

Contains  both  ferrous  and  ferric  iron,  and  much 
calcium. 

Babingtonite. 

METALLIC   LUSTEK. 

r  only  Slowly  or  Partially  Volatile. 

tie,  and  when  fused  alone  in  the  reducing  flame  do  not  become  magnetic. 

or  only  slightly  acted  upon. — Concluded. 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Fusi- 
bility. 

Crystalli- 
zation. 

e(Al.OH)SiO4. 

Pale-green  or 
blue  to  white. 

Vitreous, 
pearly. 

C.  Pinac.,  per. 
b\  Uneven. 

7.5 

3.05-3.1 

5-5.5 

Monocl. 

*Mg3Si4012. 

White,  gray, 
violet. 

Vitreous, 
pearly. 

3.  Prism.,  per. 
F.  Uneven. 

5-G 

3.00 

4 

Vlouocl. 

l(Mg,Fe)3Si4O12. 

Green  of 
various  shades. 

Vitreous, 
pearly. 

3.  Prism.,  per. 
F.  Uneven. 

5-6 

3-3.05 

4 

t 

ftonocl. 
Prismatic. 

CaMg3Si4On. 

Na2Al2Si4Oia. 

Mg2Al4Si2O12. 
Fe  iso.  w.  Mg  &  Al. 

Green  to 
black. 

Vitreous. 

3.  Pri>m.,  per. 
F.  Uneven. 

5-6 

3.2-3.3 

3-4 

tfonocl. 
U.  ciyst 
Page  212. 

Na2Al.,Si4O12. 
Mg4Si4O12. 

i  &  Fe  iso.  w.  Mg. 

Lavender-  to 
azure-  blue. 

Vitreous, 
pearly. 

C.  Prism.,  per. 
F.  Uneven. 

6-6.5 

3.1 

3-3.5 

tlonocl. 

J.  mass. 

aMgSi2O6. 

Colorless, 
white,    pale- 
green. 

Vitreous. 

C.  Prismatic. 
F.  Uneven. 

5-6 

3.29 

4 

tfonocl. 
U.  cryst. 

a(Mg,Fe)Si2O6. 

Light  to  dark- 
green. 

Vitreous. 

C.  Prismatic. 
F.  Uneven. 

5-6 

3.1-3.5 
U.3.3 

4 

Vlouocl. 
U.  cryst. 
Page  21  1. 

aFeSi206. 

Greenish-black 
to  black. 

Vitreous. 

C.  Prismatic. 
F.  Uneven.     , 

5-6 

3.55 

4 

Monocl. 

CaMgSi2O«. 
Mg-Al2SiO8. 
NaAlSi2O«. 

e  iso.  w.  Mg  &  Al. 

Greenish-black 
to  black. 

Vitreous. 

C.  Prismatic. 
F.  Uneven. 

5-6 

3.35- 

3.45 

4-4.5 

Monocl. 
Figs.  335 
&336. 

Page  21*. 

TaAlSi.O,. 

White,  grayish, 
greenish. 

Vitreous. 

C.  Prismatic. 
F.  Splintery. 

7 

3.33 

2.5 

Monocl. 
U.  mass. 

INaBeSiaOa. 

White. 

Vitreous, 
pearly. 

C.  Basal,  per. 

6 

2.55 

2.5-3 

Mouocl. 
U.  tabuL 

I3Mg3(Si03)4. 

Apple-green, 
gray,  white. 

Pearly, 
greasy. 

C.  Basal,  per. 

1 

2.80 

5-5.5 

Foliated. 
Compact. 

$(Ca,Fe,Mn)SiO3. 
iFe2(Si03)3. 

Greenish-black 
to  black. 

Vitreous. 

C.  1  dirvc.,  per. 
F.  Uneven. 

5.5-6 

3.34- 
3.40 

3-3.5 

Triclinkx 
U.  cryst.. 

(Page  289.) 


II.  MINERALS   WITHOUT   METALLIC   LUSTER. 


C.— Infusible  or  Very  Difficultly  Fusible. 

DIVISION  1. — After  intense  ignition  before  the  blowpipe,  either  in  the  forceps  or  on 
charcoal,  the  ignited  material  gives  an  alkaline  reaction  when  placed  «n 
moistened  turmeric-paper. — In  part. 


289  II.   MINERALS   WITH01 

C.— Infusible  or  ^ 

DIVISION  1. — After  intense  ignition  before  the  blowpipe,  either  in  the  forceps  or  on  chare 
N.B. — The  minerals  in  this  division  are  chiefly  the  salts  of  the  all 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

Carbon  tea.  —  The  powdered  mineral  effervesce*  or  gives  off  carbon  dioxide  gas  when  treated  in  a  test-tube 
with  dilute  hydrochloric  acid  (p.  62,  §  1).  It  is  often  necessary  to  warm  the  acid,  in  which  case  boiling 
must  i  ot.  be  mistaken  for  effervescence. 

On  intense  ignition  B.  B. 
throws  out  fine  branch- 
es aud  gives  a  crimson 
flame  (strontium). 

The  rather  dilute  HC1  solution  gives  a  precipitate 
upon  addition  of  a  few  drops  of  dilute  H2SO4 
(p.  117,  £3). 

STRONTIANITE. 

On  intense  ignition  B.  B. 
fives  a  yellowish-green 
ame  (barium). 

The  dilute  HC1  solution  gives  a  precipitate  upon 
addition  of  a  few  drops  of  dilute  HaSO4  (p.  52, 
§3).      Crystals  of  Bronilite  generally  have  a 
hexagonal  aspect. 

Barytocalcite. 

Bromlite. 

B.  B.   swells   and    colors 
the  flame  intensely  yel- 
low (sodium). 

Assumes  a  blue  color  when  moistened  with  cobalt 
nitrate  and  intensely  ignited  (aluminium). 

Dawsonite. 

Contain       calcium.  —  Dis- 
solve 2  ivory-spoonfuls 
of  the  powdered  mineral 
in3cc.  of  HC1(  wanned 
if  necessary).      Divide 
into  two  parts,    dilute 
one    with    10     cc.     of 
water,  and   add   a  few 
drops  of  dilute  H2SO4 
to  each.      The  concen- 
trated solution   gives  a 
precipitate    of    calcium 
sulphate  (p.  59,  §  8),  but 
no  precipitate  forms  in 
the  dilute  solution,  thus 
showing  the  absence  of 
strontium  and  barium. 

Imparts  to  the  salt  of  phosphorus  bead  in  R.  F. 
a  green  color  (uranium}. 

Uranothallite. 
(Liebigite.) 

Gives  much   water   in    the   closed    tube.      The 
dilute  HC1   solution  gives  a  precipitate  with 
barium  chloride  (p.  122,  §  1).     See  p.  273. 

Thaumasite. 

Fragments  effervesce  freely  in  cold  dilute  HC1. 
Crystals  of  aragonite  fall  to  a  powder  (change 
to   calcite)  wlieu    heated   below   redness   in    a 
closed    tube.      Show    marked    differences    in 
cleavage  and  specific  gravity. 

CALCITE. 

(Marble,  Limestone 

ARAGONITE. 

Fragments    effervesce    freely    in    hot,    but    not 
in   cold,   dilute  H(J1.      Test  for  magnesium  as 
directed  on  p   91,  §1,  b. 

DOLOMITE. 

(Pearl  Spar.) 

B.    B.    becomes   black   and    slightly    magnetic. 
Gives  a   considerable   reaction  for  iron  when 
tested  as  directed  on  p.  91,  §  1,  b. 

Ankerite. 
(Ferriferous    Do! 
mite.) 

Contain        magnesium.  — 
Give    a    precipitate    of 
ammonium  magnesium 
phosphate  when    tested 
as  directed    on   p.   91, 
§1,6. 
With    the    exception   of 
Magnesite   and   Breun- 
nerite,    these    minerals 
give     abundant    water 
when  heated  in  a  closed 
tube. 
The  magnesium  minerals, 
when  pure,  do  not  give 
very    decided    alkaline 
reactions  with  turmeric- 
paper. 

Scarcely  acted  upon  by  cold,  dilute  HC1.  Breun- 
nerite   gives   a  considerable   reaction  for  iron 
when  tested  as  directed  on  p.  91,  §  1,  b. 

MAGNESITE. 

Breunnerite. 
(Ferriferous    Ma 
nesite.) 

Fragments  are  scarcely  acted  upon  by  cold,  di- 
lute HC1. 

Hydromagnesite. 

Whitens,  and  alters  to  Nesquehonite  on  expos- 
ure to  dry  air. 

Lansfordite. 

Occurs  in  spherical  aggregations. 

Hydrogioberite. 

Soluble  in  cold,  dilute  HC1.                                       Nesquehonite. 

Some  varieties  of  Siderite,  FeCO3,  Rhodonite,  MnCO3,  nud  Smithsonite,  ZnCOs  (Division  2 

DIVISION  1.— Concluded  on  next  page. 


METALLIC   LUSTER. 
y  Difficultly  Fusible. 

the  ignited  material  gives  an  alkaline  reaction  when  placed  on  moistened  turmeric-paper. 
earth  metals,  calcium,  strontium,  and  barium,  with  volatile  acids. 


289 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Crystalli- 
zation. 

C08. 

White,  gray, 
yellow,  green. 

Vitreous. 

C.  Prismatic. 
F.  Uneven. 

3.5-4 

3.70 

Orthorh. 
Column. 

aBa(CO3)2. 

- 

White,  giay, 
yellow,  green. 

Vitreous. 

C.  Prism.  ,  per. 
F.  Uneven. 

4 

3.65 

Mouocl. 
Prismat. 

Orthorh. 
Pyramid. 

:a,Ba)CO3. 

White,  gray, 
cream-color. 

Vitreous. 

F.  Uneven. 

4-4.5 

3.7 

a(A1.2OH)CO8. 

White. 

Vitreous, 
silky. 

F.  Longitudi- 
nal. 

3 

2.40 

Monocl. 
Radiated. 

a2U(CO3)4.10H2O. 

Yellowish- 
green. 

Vitreous, 
pearly. 

C.  One  direc- 
tion. 

2.5-3 

Orthorh. 
Tabular. 

aCO3.CaSiO3.CaSO4. 
15H2O. 

White, 
colorless. 

Vitreous. 

F.  Splintery. 

3.5 

1.87 

Hexag. 
B'ibrous. 

ElCO3. 

Colorless, 
white,  and  va- 
riously tinted. 

Vitreous. 

C.  Rhombo- 
hedral,  per. 

3 

2.72 

Hex.  Rh. 
Page  192. 

aCO3. 

Colorless, 
white,  and  va- 
riously tinted. 

Vitreous. 

C.  Piuac.,jt)00r. 
F.  Uneven. 

3.5-4 

2.95 

Orthorh. 
Page  205. 

aMg(CO8)«. 

e  iso.  w.  Mg. 

Colorless, 
white,  and  va- 
riously tinted. 

Vitreous, 
pearly. 

C.  Rhombo- 
hedral,  per. 

3.5-4 

2.85 

Hex.  Rh. 

Cl.  14,  p.^19. 

a(Mg,  Fe,Mn)(CO3)2. 

Brown,  gray, 
seldom  white. 

Vitreous, 
pearly. 

C.  Rhombo- 
hedral,  per. 

3.5-4 

2.95-3.1 

Hex.  Rh. 

Cl.  14,  p.  219. 

gC03. 

White,  yellow, 
gray,  brown. 

Vitreous, 
pearly. 

C.  Rhombo- 
hedral,  per. 

3.5-4.5 

3.0-3.1 

Hex.  Rh. 
U.  gran. 

Hex.  Rh. 

Hg,Fe)COs. 

Brown,  gray, 
seldom  white. 

Vitreous. 

C.  Rhombo- 
hedral,  per. 

3.5-4.5 

3.0-3.2 

:g3(Mg.OH)2(CO3)3. 
3H20. 

White. 

Vitreous, 
silky. 

3.5 

2.15 

Monocl. 
U.  acic. 

[g2(Mg.OH)2(C03)3. 
21H20. 

Colorless, 
white. 

Paraffin-like. 

C.  Basal. 

2.5 

1.5-1.7 

Triclinic. 

tfg.OH)2C03.2H20. 

Light-gray. 

2.16 

Compact. 

[gCO3.3H2O. 

Colorless, 
white. 

V^eous.          £  1™-.  r 

2.5 

1.84 

Orthorh. 
Prismat. 

utaiti  sufficient  calcium  to  cause  them  to  give  an  alkaline  reaction  after  ignition. 

(Page  290.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

C.— Infusible  or  Very  Difficultly  Fusible. 

DIVISION  1. — After  intense  ignition  before  the  blowpipe,  either  in  the  forceps  or  on 
charcoal,  the  ignited  material  gives  an  alkaline  reaction  when  placed  on 
moistened  turmeric-paper. — Concluded. 

DIVISION  2.— Soluble  in  Hydrochloric  acid,  but  do  not  yield  a  jelly  or  a  residue  of  silica 
upon  evaporation. — In  part. 


290  II.   MINERALS   W1THOV 

« 

C.— Infusible  or  Ve 
DIVISION  1.— After  intense  ignition  before  the  blowpipe,  either  in  the  forceps  or  on  charcoal,  th 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

Easily    and    quietly    soluble    in 
warm  HC1.    Gives  the  reaction 
for  magnesium  (p.  91,  §1). 

B.  B.  glows.  Gives  water  in  the  closed  tube. 
Yields  only  a  slight  alkaline  reaction.  Some- 
times fibrous.  §W°  Compare  Periclase  (p.  291). 

BRUCITE. 

Sttlnhntes.—  Given  cid  water  in  the 
closed  tube,  accompanied,  after 
intense  ignition,  by  the  odor  of 
sulphur  dioxide  (p.  123,  §  3). 

Ignited,  then  moistened  with  cobalt  nitrate  and 
again  ignited,  assumes  1)1  ue  color  (aluminium). 
Kalinite  is  readily  soluble  in  water,  while  alu- 
nite  is  scarcely  attacked  by  noids. 

Kalinite. 

(Potash  Alum). 

Alunite. 

Sulphide.  —  Soluble  in  HC1  with  evolution  of  hydrogen  sulphide  (p,   121,  §  7) 
Found  only  in  meteorites. 

Oldhamite. 

Fluoride.  —  When  intensely  heated  in  the  closed  tube  gives  acid  water  and  vapor^ 
which  corrode  the  glass  (p.  77,  §  5).     B.  B.  shows  slight  indication  of  fusion. 
Gives  only  a  slight  alkaline  reaction. 

Prosopite. 

Oxalate.  —  Quietly  soluble  in  warm  HC1.     When  hen  ted  below  redness  in  a  closed 
tube,  crumbles,  yields  water  and  carbon  monoxide  gas,  and  changes  to  CaCO3. 
which  will  effervesce  with  acids. 

Whewellite. 

DIVISION  2. — Soluble  in  hydrochloric  acid,  but  do  \ 

In  order  to  determine  that  a  mineral  belongs  to  this  division,  treat  one  or  two  ivory-spoonful 
until  not  over  1  cc.  remains.  The  concentrated  solution  thus  obtained  should  be  a  clear  liquid  (nc 
the  solution  or  deposits  on  sides  of  the  tube  it  should  dissolve  completely  upon  addition  of  water  an 


carbon  di- 
drochloric 
1  serve  to 
youd. 

Contains  nickel.—  Imparts  to  the  borax  bead  in  O.  F.  a  violet  color  when 
hot,  changing  to  brown  when  cold.     Gives  water  in  the  closed  tube. 

Zaratite. 

(Emerald  Nickel.^ 

Contains  ma  nganete.  —  Imparts  to  the  borax  bead  in  O.  F.  a  reddish-violet 
color.     Some  varieties  contain  sufficient  iron  to  cause  them  to  become 
magnetic  after  heating  B.  B. 

RHODOCHROSITE 

(Diallogite.) 

*-  c    -  ~ 

Contain   zinc.  —  Gives  a 
zinc  flame,  and  a  coat- 
ing of  zinc  oxide  on 
charcoal,  when  heat- 
ed as  directed  on  p. 
181,  §l(Fig  49). 

Gives  little  or  no  water  in  the  closed  tube. 

SMITHSONITE. 

(Dry-bone  Ore.) 

Give  water  in  the  closed  tube.  Aurichalcite  gives 
an  azure-blue  flame  (copper)  when  moistened 
with  HC1  and  heated  on  charcoal  B.  B.  (p.  72. 

§1). 

Aurichalcite. 

Carbonates.—  The  powdered  mineral  effervesces  o 
oxide  gas  when  treated  in  a  test-tube  with  warr 
acid  (p.  62,  §1).  The  absence  of  a  disagreea! 
distinguish  carbon  dioxide  from  hydrogen  sulp 

Hydrozincite. 

Contain  cobalt.  —  Impart 
to  the  borax   bead  a 
blue  color. 

Gives  little  or  no  water  in  the  closed  tube. 

Sphserocobaltite. 

Gives  water  in  the  closed  tube. 

Remingtonire. 

Contain  iron.—  Become 
black    and    magnetic 
when    heated    B.    B. 
React  for  ferrous  iron 
with  potassium  ferri- 
cyanide  (p.  8~>.  §  4). 

Give   reactions    for   both  magnesium    and   iron 
when  tested  as  directed  on  p.  91,  §  1,  b. 
USSF"  Compare  Ankerite  (p.  289). 

Breunnerite. 

(Ferriferous    Ma 
nesite.) 

Give  slight  or  no  reactions  for  magnesium  and 
calcium  when  tested  as  directed  on  p.  91, 
§  1,  b.  Fus.  =  5  5-6. 

(Spathic  'iron.) 

Give   reactions  for   the 
rare-earth  metals  (p. 
>65). 

Give  the  reaction  for  fluorine  (p.  76,  §3). 
(H^~  Compare  Bastnasite  (p.  297),  which  is  slowly 
dissolved  by  HC1. 

Par  i  site. 

Gives  only  a  slight  ef- 
fervescence with  HC1. 

Gives  reactions  for  calcium  (p.  59,  §3)  and  for  a 
phosphate  (p.  102,  §  1). 

Dahllite. 

Give  the  test  for  mag- 
nesium, when  treated 
as  directed  on  p.  91, 
§  1  . 

03F"  Compare  magnetite  and  other  magnesium 
carbonates  on  p.  289,  which  give  a  faint  alka 
line  reaction  after  ignition. 

MAGNESITE. 

DIVISION  2.— Continued  on  next  page. 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Crystalli- 
zation. 

g(OH)a.              ^ 

&  Mn  iso.  w.  Mg. 

White,  gray, 
green. 

Pearly, 
vitreous. 

C.  Basal,  per. 

2.5 

2.39 

Hex.  Rh. 
U.  tabul. 

AJ(S04)a.12HaO.    2 

Colorless, 
white. 

Vitreous. 

F.  Conchoidal. 

2-2.25 

1.75 

Isom.Pyr. 
U.  fibrous. 

,Na)(A1.2OH)s(SO4)a. 

White,  gray. 

Vitreous. 

C.  Basal. 
F.  Uneven. 

3.5-4 

2.83 

Hex.  Rh. 
U.  tabul 

18. 

Pale  chestnut- 
brown. 

C.  Cubic. 

4 

2.58 

Isometric. 

iFa.2Al(F,OH),. 

Colorless, 
white,  gray. 

Vitreous. 

C.  Prismatic. 
F.  Uneven. 

4.5 

2.89 

Monocl. 

iC2O4.H3O. 

Colorless, 
white. 

Vitreous. 

C.  Pinacoidal. 
F.  Conchoidal. 

2.5 

2.23 

Monocl. 

METALLIC   LUSTER.  290 

Difficultly  Fusible. 

lited  material  gives  an  alkaline  reaction  when  placed  on  moistened  turmeric-paper.— Concluded. 


field  a  jelly  or  a  residue  of  silica  upon  evaporation. 

the  finely  powdered  material  in  a  test-tube  with  from  3  to  5  cc.  of  hydrochloric  acid,  and  boil 
ick  and  gelatinous,  indicating  a  silicate,  division  3),  or  in  case  any  solid  material  separates  from 
arming. 


ii.OH)aCO3.Ni(OH)2. 
4H2O. 

Emerald-           iyitreous. 
green,     i 

F.  Smooth. 

3-3.25 

2.6-2.7 

Massive. 
Compact. 

nCO3. 

L.  Fe,  Mg  &  Zn  iso.  w.  Mn. 

Rose-red, 

dark  -red, 
brown. 

Vitreous, 
pearly. 

C.  Rhombo- 
hedral,  per. 

3.5-4.5 

3.45- 
3.60 

Hex.  Rh. 

|Brown,  green, 
iCOs-                                        blue,  pink, 
,  Mg,  Fe,  Mn  &  Co  isq.w.Zn.      wujte 

C.  Rhoui  bo- 
Vitreous,               hedral,  per. 
F.  Uneven. 

5 

- 

4.30- 
4.35 

Hex.  Rh. 
U.  botry., 
Fig.  363. 

Zn,Cu)CO8. 

3(Zn,Cn)(OHV 

Pale-green  to 
blue. 

Pearly. 

'2 

3.6 

Monocl. 
U.  acic. 
Earth}'. 
Compact. 

:nCO3.3Zu(OH)2? 

White,  gray, 
yellow. 

Dull. 

2-2.5 

3.6-3.8 

oCOs. 

Rose-red. 

Vitreous. 

4 

4.0-4.13 

Hex.  Rh. 

n  certain. 
vd  ruled  GoCO3. 

Ro«e-red. 

Soft. 

Earthy. 

lg.Fe)CO,. 

Brown,  gray, 
seldom  white. 

Vitreous. 

C.  Rhombo- 
hedral,  per. 

3.5-4.5 

3.0-3.2 

Hex.  Rh. 

eCO,. 

i,  Mg  &  Mn  iso.  w.  Fe. 

Brown  ot 
different 
shades. 

Vitreous, 
pearly. 

C.  Rhombo- 
hedral,  per. 

3.5-4 

3.85 

Hex.  Rh. 

a(CeF)a(CO,),. 

<t  La  iao.  w.  Ce. 

Yellowish- 
brown,  brown. 

Vitreous, 
resinous. 

C.  Basal,  per. 
F.  Uneven. 

4.5 

4.36 

Hexag. 
Pyram. 

a7(CO,)(PO4)4.1H,O. 

Pale  yellow- 
ish-white. 

Resinous. 

F.  Splintery. 

5 

3.05 

Fibrous. 

gC03. 

White,  yellow, 
gray,  brown. 

Vitreous, 
pearly. 

C.  Rhombo- 
hedral,  per. 

3.5-45 

3.0-3.1 

Hex.  Rh. 
U.  gran. 

(Page  291.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

C.— Infusible  or  Very  Difficultly  Fusible. 

DIVISION  2.— Soluble  in  hydrochloric  acid,  but  do  not  yield  a  jelly  or  a  residue  of  silica 
upon  evaporation. — Continued. 


2&JL 


LS   WITH01 


II.   MINERAL 

C.— Infusible  or  Ve 
DIVISION  2. — Soluble  in  .hydrochloric  acid,  but  do  not  yiel 


General  Characters. 

Specific  Characters.                                       Name  of  Species. 

irium  chloiide 
ran  da  distinct 
3). 

Iraparis  to  the  borax  bend  a  blue  color  (cobalt}.                                                  Bieberite. 

Imparts  to  the  borax  bead  in  O.  F.  a  violet  color  when  hot,  changing  to 
brown  when  cold  (nickel). 

Morenosite. 

Szmikite. 

o  P  c5 
|1* 

Impart  to  the  borax  bead  in  O.  F.  a  reddish-violet  color  (manganese).  — 
Apjohnite  and  Dietrichite  give  an  abundant  precipitate  of  aluminium 
hydroxide  when  ammonia  is  added  to  the   HC1   solution.     Ilesite  and 
Dietrichite  give  a  coating  of  zinc  oxide  when  intensely  ignited  on  charcoal 
in  R.  F. 

Mallardite. 

Ilesite. 

tion  gives  a  precipitate  upon  nd 
c-rals  in  this  section  give  strong! 
intensely  heated  in  a  closed  tub 

Apjohnite. 

Dietrichite. 

Imparts  to  the  salt  of  phosphorus  bead  in  O.  F.  a  pale  yellowish-green 
color,  which  is  changed  to  a  fine  green  in  R.  F.  (uranium). 

Johannite. 

Uranopilite. 

Contain      aluminium*  — 

Gives  little  or  no  water  in  the  closed  tube. 

Alumian. 

B.  B.  gives  a  violet  flame  (potassium).   Kaliuite  is 
readily  soluble  in  water.    Lowigite  is  insoluble 
in  water  and  difficultly  soluble  in  HC1. 

Kalinite. 
(Potash  Alum.) 

.5.5  a 

0   Z   <» 

cfl  —  ,3 

First      ignited,      then 
moistened   with  cobalt 
nitrate,    and    again  in- 
t  en  sly  ignited,  assume  a 
blue  color  (p.  42,  81). 
E2f~  Compare  zincalumi- 
nite  below. 

Lowigite. 

111 

O    |    3 
»<  ^   O 

f^' 

Gives  the  odor  of  ammonia  when  heated  in  a 
closed  tube  with  lime  (ignited  calcite). 

Tschermi#ite. 
(Ammonia  Alum. 

Soluble  in  water. 

Alunogen. 

Insoluble  in  water. 

Alumiuite. 

FelsQbanyite. 

Gives  a  coating  of  zinc  oxide  when  intensely  heated  on  charcoal  in  R.  F. 

Zincaluminite. 

Goslarite. 

DIVISION  2. — Continued  on  next  page. 


METALLIC   LUSTEJt. 

Difficultly  Fusible. 

lly  or  a  residue  of  silica  upon  evaporation. — Continued. 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Crystalli- 
zation. 

S04.7H8O. 

FJesh-  to  rose- 
red. 

Vitreous. 

1.92 

Monocl. 
In  crust. 

*O4.7H20. 

Apple-green  to 
greeuish- 
white. 

Vitreous. 

C.  Pinacoidal. 

2 

2.00 

Orthorh. 
U.  acic. 

SO4.H2O. 

White  to  pink. 

1.5 

3.15 

Amorph. 
Botry. 

SO4.7HSO. 

Pink  to  white. 

Mouocl. 
U.  fibrous. 

l,Zn,Fe)SO4.4H20. 

Green  to  white. 

Monocl.  ? 
Prismatic, 

A12(SO4)4.24H2O. 

White  to  pale 
rose. 

Silky. 

1.5 

1.78 

Monocl.? 
U.ribrous. 

,Fe,Mn)Al2(SO4)4. 
22H2O. 

Dirty-white  to 
browuish- 
yellow. 

Silky. 

Monocl.  ? 
U.  fibrous. 

i'ert;iin. 
>4),U,Cu,H2O. 

Emerald- 
green. 

Vitreous. 

2-2.5 

3.19 

Monocl. 
Tabular. 

LSaO^SSHjO? 

Yellow. 

8.75- 

3.95 

Velvety 
ncrust. 

2O)(S04)2. 

White. 

Vitreous. 

2-3 

2.75 

Massive. 

1(S04)2.12H20. 

Colorless, 
white. 

Vitreous. 

F.  Conchoidal. 

2-2.5 

1.75 

[som.Pyr 
U.  fibrous. 

U2OH)3(SO4)2.HH2O. 

Straw-yellow. 

Vitreous. 

F.  Conchoidal. 

3-4 

2.58 

Mussive. 

i4Al(SO4)2.12H2O. 

Colorless, 
white. 

Vitreous. 

F.  Conchoidal. 

1-2 

1.50 

Lsom.Pyr. 
U.  fibrous. 

(SO4)s.18HaO. 

White. 

Vitreous, 
silky. 

1.5-2 

1.6-1.8 

Monocl. 
U.  fibrous 

(OH)4S04.7H20. 

White. 

Dull. 

F.  Uneven. 

1-2 

1.66 

Monocl. 
U.  Renif 

(OH)4SO4.2A1(OH)3. 
5H80. 

White. 

Pearly. 

C.  Perfect. 

1.5 

2.33 

Orthorh. 
U.  scales. 

Al«SaOa6.18H9O. 

White,  bluish- 
white. 

2.5-3 

2.26 

iexag. 
J.  tabular 

504.7H.O. 

White. 

Vitreous. 

C.  Piuac.,  per. 

2-25 

1.95- 
2.04 

Orthorh. 
Acicular. 

(Page  292.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTEK. 

C.— Infusible  or  Very  Difficultly  Fusible. 

DIVISION  2.-- Soluble  in  hydrochloric  acid,  but  do  not  yield  a  jelly  or  a  residue  of  silica 
upon  evaporation.— Continued. 


292 


II.   MINERALS   WITHO 

C.— Infusible  or  Ve: 

DIVISION  2. — Soluble  in  hydrochloric  acid,  but  do  not  yie( 


General  Characters. 

Specific  Characters, 

Name  of  Species. 

Sulphides.  —  Decomposed  by 
warm  HC1  with  evolution  of 
hydrogen  sulphide  gas,  which 
may  be  detected  by  its  odor. 

Give  a  coating  of  zinc  oxide  on  charcoal  (yellow 
when  hot,  white  when  cold)  when  heated  as 
directed  on  p.  131,  §  1  (Fig.  49). 

SPHALERITE. 

(Zinc  Blende.) 
See  p.  252. 

Wurtzite. 

Voltzite. 

Gives  a  reddibh-browu  coating  of  cadmium  oxide 
when  heated  on  charcoal  in  R.  F.  with  a  little 
Na2CO3. 

Greenockite. 

^/ 

Contain  iron.  —  When  heated  in 
R.F.  become  strongly  mag- 
netic. With  the  exception  of 
Pyroaurite  become  black  when 
heated  B.B.  and  fuse  when  in 

Streak  brownish-red  (Indian-red,  red-ocher). 
Hematite  is  anhydrous  or  nearly  so.  Turgite 
gives  water  (5  per  cent)  in  the  closed  tube  and 
generally  decrepitates. 

HEMATITE. 
Fig.  262.     See  p.  25 

Turgite 

(Hydro-hematite. 

Streak  yellowish-brown  (yellow-ocher).  Give 
water  in  the  closed  tube. 

GOETHITE. 

(Gothite.) 

Completely,    though    somewhat 
slowly,  soluble  in  HC1.     The 
solution   is  yellow,  and,   with 
the  exception  of  Symplesite.re- 
acts  for  ferric  iron  with  potas- 
sium ferrocyanide  (p.  85,  §  4). 
ISF"  Compare  Bumenite   below, 
which  also  becomes  magnetic. 

LIMONITE. 

(Brown  Hematite 
Bog  Iron  Ore.) 

Xanthosiderite. 

Gives  a  decided  reaction  for  magnesium  after 
separation  of  the  iron  (p.  91,  §  1,  b). 

Pyroaurite. 

Gives  the  reaction  for  an  arseuate  when  intensely 
heated  in  a  closed  tube  with  splinters  of 
charcoal  (p.  51  ,  §  a). 

Symplesite. 

Contains  nickel.—  Colors  the 
borax  bead  in  O.F.  violet  when 
hot  and  brown  when  cold. 

Magnetic  after  heating  in  R.  F. 

Bunsenite. 

Contain  manganese.—  Impart  to 
the  borax  bead  in  O.  F.  a  red- 
dish-violet color  which  be- 
comes colorless  in  R.  F. 

Gives  a  coating  of  zinc  oxide  when  the  finely 
powdered  mineral  is  intensely  heated  B.  B.  on 
charcoal  with  a  little  Na3CO3. 

ZINCITE. 
(Red  Zinc  Ore.) 

jKves  a  coating  of  oxide  of  antimony  when  heat- 
ed with  a  little  Na2CO3  on  charcoal  in  R.  F. 

Manganostibite. 

Anhydrous.  The  color  of  the  unaltered  mineral  is 
very  characteristic.  Darkens  on  exposure. 

Manganosite. 

Gives  water  in  the  closed  tube.  Color  white  when 
fresh,  but  darkens  on  exposure. 

Pyrochroite. 

Structure  earthy,  pulverulent  and  frothy.  Gives 
water  in  the  closed  tube. 

Wad. 
(Bog  Manganese.) 

Give  an  arsenical  mirror  when  intensely  heated 
in  a  closed  tube  with  NaaCOs  and  charcoal 
powder  (p,  51,  §  b). 

Allactite. 

Hematolite. 

Contains  cobalt.  —  Imparts  to  the 
borax  bead  a  blue  color. 

Gives  a  green  color  to  the  NaaCO3  bead  in  O.  F. 
(manganese).                                   rt 
jives  water  in  a  closed  tube. 

Asbolite. 

DIVISION  2. — Concluded  on  next  page. 


METALLIC   LUSTER. 
Difficultly  Fusible. 

telly  or  a  residue  of  silica  upon  evaporation. — Continued. 


292 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Crystalli- 
zation. 

S. 
and  often  a  small  amount 
»f  Cd  iso.  w.  Zn. 

White,  green, 
yellow,  brown, 
black. 

Resinous, 
adamantine. 

C.  Dodecahe- 

dral,  per. 

3.5-4        4.10 

Isom.  Tet. 
Page  175. 

S. 

Brown  to 
brown-black. 

Resinous. 

C.  Prismatic. 

3.5-4       3.98 

Hexag. 
Hemimor. 

nS.ZnO. 

Rose-red,  yel-    Vitreous, 
low,  brown,  j               greasy. 

4-4.5 

JJ.tio- 

3.80 

Globular. 

IS. 

Honey  -,  citron  - 
or  orange- 
yellow 

Adamantine, 
resinous. 

C.  Prismatic. 
F.  Uneven. 

3-3.5 

4.9-5.0 

Hexag. 
Hemimor. 

aOs. 

Red  to  reddish-  Dull  to  sub- 
black.            1     metallic. 

F.  Splintery. 

5.5-6 

4.9-5.2 

Compact. 
Earth}'. 

4O6(OH)2= 
2FeaO,.H3O. 

Red  to  reddish- 
Hack. 

Dull  to  sub- 
metallic. 

F.  Splintery. 

5-6 

4.14 

Incrust. 
Mammill. 

O(OH)  =  2FeO,.2H3O. 

Yellow,  brown 
to  brownish- 
black. 

Dull  to 
adamantine. 

C.  Pinac.,  per. 
F.  Splintery. 

5-5.5  ' 

4.37 

Orthorh. 
Prismatic 

403(OH)8  = 
2Fea08.3H3O. 

Yellow,  brown 
to  brownish- 
black. 

Silky,  dull, 
earthy. 

F.  Splintery. 

5-5.5 

3.6-4.0 

Radiated. 
Stalactitic 

20(OH)4  = 
2FeaO».4H,O. 

Golden-yellow 
to  brown. 

Silky,  pitch- 
like,  earthy. 

2.5 

Acicular. 
Earthy. 

(OH),.3Mg(OH),.3HaO 

Golden-yellow 
to  silver-white. 

Pearly. 

2-3 

2.07 

Hexag. 
Tabular. 

3(As04)3.8HaO. 

- 
Blue  to  inoun- 
tain-greeu. 

Pearly, 
vitreous. 

C.  Pinac.,  per. 
F.  Uneven. 

2.5 

2.95 

Monocl. 
Prismatic 

O. 

Pistachio- 
green. 

Vitreous. 

5.5 

6.40 

Isometric. 

i,Mn)O. 

Deep-red  to 
orange-yellow. 

Adamantine. 

C.  Basal,  per. 

4-4.5 

5.5-5.55 

Hexag. 
Hemimor 
Page  190, 

iso.  w.  Sb. 

Black. 

Compact. 

lO. 

Dark  emerald- 
green. 

Vitreous, 
adamantine. 

C.  Cubic,  per. 

5-6 

5.18 

Isometric, 

i(OH)a. 

White  to 
bronze. 

Pearly. 

C.  Basal,  per. 

2.5 

3.26 

Hex.  RLu 
Tabular. 

i  pure  hydrated  oxide  of 
nanganese. 

Gray,  brown, 
dull-black. 

Dull. 

Massive. 
Earthy. 

Monocl 

is(  AsO4  ^a  .  4Mn(OH)t* 

Brownish  -red. 

Vitreous, 
greasy. 

C.  One  direc. 
F.  Uneven 

4.5 

3.84 

l,Mn)AsO4.4Mn(OH)2. 

Brownish-  to 
garnet-red. 

Vitreous, 
greasy. 

C.  Basal,  per. 
F.  Uneven. 

3.5 

3.35 

Hex.  Rh. 

•drated  cobalt  and  man- 
ganese oxides.    •> 

Brown,  black. 

Dull. 

Massive. 
Earthy. 

(Page  293.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTEE. 

C.— Infusible  or  Very  Difficultly  Fusible. 

DIVISION  2. — Soluble  iu  hydrochloric  acid,  but  do  not  yield  a  jetty  or  a  residue  of  silica 
upon  evaporation. — Concluded. 


293 


II.   MINERALS   WITHC 

C.— Infusible  or  V< 

DIVISION  2. — Soluble  in  hydrochloric  acid,  but  do  not  yi 


General  Characters. 

Specific  Characters. 

Name  of  Species 

pitale  of  ammonium  phos- 
2,  §  1).  The  pale,  Uuish- 
f  seen  after  moistening  the 
lo  identify  a  phosphate. 

Contain  calcium.  —  The 
cold,  concentrated  HC1 
solution   gives  a  pre- 
cipitate    of      calcium 
sulphateupon  addition 
of  a  few  drops  of  dilute 
H3S04  (p.  59.  §  3). 

Gives  a  slight  reaction  for  fluorine  (p.  75,  §  1)  and 
generally  also  for  chlorine  (p.  67,  §1). 

APATITE. 

Gives  water  in  the  closed  tube. 

Martinite. 

Contain  aluminium  and 
water.  —  The     ignited 
minerals,  when  moist- 
ened   with    cobalt    ni- 
trate and  intensely  ig- 
nited   B.  B..  assume  a 
blue  color  (p.  42,  §  1). 
Give     water     in     the 
closed  tube. 
When  crystals   are   not 
available,  quantitative 
determinations           of 
some  of  the  constitu- 
ents will  be  needed  in 
order  to  make  a  sure 
identification  of  these 
rare  phosphates. 
Jg^~  Compare     the     in- 
soluble   or    difficultly 
soluble  phosphates  on 
p.  296.    It  is  probable 
that  some  of  the  min- 
erals in  this  section  are 
insoluble  in  HC1. 

26.9  per  cent  of  water. 

Callainite. 

30.7  per  cent  of  water. 

Zepharovichite. 

34.0  per  cent  of  water. 

Minervite. 

«    c  °  •—  • 

=  ac.5  a 

37.1  per  cent  of  water. 

Gibbsite. 

ammonium  molybdate  a  yellow 
phomolybdate  is  thrown  down  ( 
green  flame  coloration  (sometime 
assay  with  HabO4)  may  also  be  \ 

13.5  per  cent  of  water. 

Augelite. 

23.8  per  cent  of  water. 

Peganite. 

29.4  per  cent  of  water. 

Fischerite. 

26.5  per  cent  of  water. 

Sphserite. 

42.0  per  cent  of  water. 

Evansite. 

Contain  the  rare-earth  metals  (p.  65).—  The  HC1  solution,  made  nearly 
neutral  with  ammonia,  gives  an  abundant  white  precipitate  upon 
addition  of  ammonium  oxulate. 
Jdp  Compare  Monazite  (p.  296),  which  is  difficultly  soluble  in  HC1. 

Rh  abd  ophan  ite. 
(Scovillite.) 

Churchite. 

/ontnin  magnesium.—  Give  a  pre- 
cipitate   of    ammonium    mag- 
nesium phosphate  when  treated 
as  directed   on   p.    91,   §1,  b. 
Jlow     with    a    brilliant    white 
light  when    intensely    ignited 
B.  B. 

The  dilute  HC1  solution  gives  with  ammonia  a 
precipitate  of  aluminium  hydroxide.      Has  a 
greasy  feel. 

Hydrotalcite. 

Give  little  or  no  water  in  the  closed  tube. 

Periclase. 

Gives  abundant  water  in  the  closed  tube.    Some- 
limes  fibrous. 

BRUCITE. 

)ontiiin  tho  rare-earth  metals.  — 
Test  :is  directed  on  p.  65. 
3^~  Compare  Bastndsite  (p.  297), 
which   is  slowly  attacked  by 
HC1. 

In  the  closed  tube  at  a  high  temperature  give 
water  which  has  a  strong  acid  reaction  (fluor- 
ine, p.  77,  §  5). 

Fluocerite. 

Yttrocerite. 

Contains  uranium.  —  Imparts  to  the  salt  of  phosphorus  bead  in  O.  F.  a  pale  yel- 
'owish-green  color,  which  is  changed  to  emerald-green  in  R.  F. 

Gummite. 

METALLIC   LUSTER. 
Difficultly  Fusible. 
elly  or  a  residue  of  silica  upon  evaporation.— Concluded. 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Crystalli- 
zation. 

4(CaF)(P04)3. 
iso.  w.  F. 

jrreeu,  blue, 
violet,  brown, 
colorless. 

Vitreous, 
greasy. 

C.  Basal. 
b\  Uneven. 

5 

3.15 

Hexag. 
Page  189. 

Ca5(P04)44H2O. 

White,  yellow. 

2.9 

Hex.  Kh. 

P04.2pI20. 

Apple-  to 
emerald-green. 

3.5-4 

2.51 

Massive. 
Wax-like. 

PO4.3HaO. 

Greenish-  to 
grayish-white. 

F.  Conchoidal. 

5.5 

2.37 

Uompact. 
Horn  -like 

P04.3|H20. 

White. 

Massive. 

P04.4HaO. 

White. 

1 

Massive. 
Foliated. 

3(OH)3P04. 

Colorless, 
white. 

V  IllCOllS, 

pearly. 

C.  Prism.,  per. 
F.  Uneven. 

4.5-5 

2.70 

Mouocl. 

2(OH)3PO4.1£H2O. 

Dark-  to  light- 
green. 

Greasy, 
vitreous. 

F.  Uneven. 

3-3.5 

2.50 

Orthorh. 
Prismatic. 

2(OH)3P04.2£HaO. 

Grass-  to  olive- 
green. 

Vitreous. 

5 

2.46 

Orthorh. 

U(OH)9(P04)a.12H20. 

Light  gray  or 
blue. 

Greasy, 
vitreous. 

C.  One  direc- 
tion 

4 

2.53 

Globular. 

13(OH)«P04.6H20. 

White,  pale- 
yellow  or  blue. 

Vitreous, 
wax-like. 

F.  Uneven. 

3.5-4 

1.94 

Msissive. 
Botryoid. 

,a,Di,Y,Er)P04.H20. 

Brown,  pink, 
yellow,  white. 

Greasy. 

F.  Uneven. 

3.5 

3.95 

Massive. 
VLimmill. 

i3Ce10(PO)4,a.24HaO? 

Sinoke-irray, 
pinkish  tone. 

Vitreous, 
pearly. 

C.  One  direc. 
F.  Conchoidal. 

3-3.5 

3.15 

Monocl.  ? 
Radiated. 

g3Al(OH)6.3H20. 

White. 

Pearly. 

C.  Basal,  per. 

2 

2.05- 
2.09 

Hexag. 
U.  foli- 
ated 

go. 

Doiorless.gray, 
dark-green. 

Vitreous. 

C.  Cubic,  per. 

5.5-6 

3.7-3.9 

Isometric. 

g(OH)9. 

White,  gray, 
ffreen. 

Pearly, 
vitreous 

C.  Basal  ,  per. 

2.5 

2.39 

Hex    Kh. 
U.  tabular 

?e,La,Di)2OF4. 

H)  iso.  w.  F. 

Reddish- 
yellow 

Resinous. 

F.  Uneven. 

4 

5.7-5.9 

Hexag. 
U.  mass. 

r,Er,Ce)F3.5CaF3.HaO. 

Violet,  gray, 
brown,  white 

Vitreous, 
pearly 

C.  Two  direc. 
F.  Uneven. 

4-5 

3.35- 
3.45 

Massive. 

'b.Ca.BayU'.SiOj^H.O 

Yellow, 
?    orange-red  U 
brow  n  . 

Greasy. 

F.  Uneven. 

2.5-3 

3.9-4.2 

Massive. 
Gum-likcv 

(Page  294.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

C.— Infusible  or  Very  Difficultly  Fusible. 
DIVISION  3. — Soluble  in  hydrochloric  acid,  and  yield  gelatinous  silica  upon  evaporation. 


294  II.   MINERALS   WITHO 

C.— Infusible  or  Ver 
DIVISION  3. — Soluble  iu  hydrochloric  acid, 

In  order  to  determine  that  a  mineral  belongs  in  this  division,  treat  one  or  two  ivory-spoonfuls  o 
not  over  1  cc.  remains.  The  mineral  should  go  wholly  into  solution,  unless  difficultly  soluble,  and 
gelatinous  silicic  acid  (p.  108,  §  1).  The  silicic  acid  thus  separated  will  not  go  into  solution  when  he? 


General  Characters. 


Specific  Characters. 


Name  of  Species. 


Contain  zinc. — Give  a  coating  of 
oxide  of  zinc  when  heated  with 
a  little  NftfCOi  on  charcoal,  or 
as  shown  in  Fig.  49  (p.  131). 


Gives  little  or  no  water  in  the  closed  tube. 


WILLEMITE.    See 
troostite,  p.  279. 


Gives  water  iu  the  closed  tube.     Exhibits  pyro- 
electricity  (p.  231). 


CALAMINE. 
(Hemimorphite.) 


Gives  a  slight  odor  of  hydrogen  sulphide  when 

dissolved  in  HC1.  Danalite.    See  p.  269 


Contains  copper.— Gives  a  globule 

of  copper  when  fused  B.  B.  IGives  water  in  the  closed  tube, 
with  NaQCO3  on  charcoal. 


Contain      magnesium.  —  Rather 
slowly  decomposed    by   HC1. 


Diopiase. 


Anhydrous.     Contains  little  or  no  iron. 


Forsterite. 


Treat  £  ivory-spoonful  of   the 

finely  powdered  material  in  a  Anhydrous. 
test-tube    with    3  cc.  of  HC11 
and     evaporate      to    dryuess. 
Then  add  3cc.  of  HC1,  a  drop! 
of  HNOs,  5  cc.  of  water,  boil 
and  filter. 
•  ammonia 

iron,  filter,  and  then  test  the1 
filtrate  with  ammonium  oxalate 
to  prove  the  absence  of  calcium | 
(p.  60,  §6)  aud  with  sodium! 
phosphate  to  prove  the  presencel 
of  magnesium  (p.  91,  §1,  b). 


Contains  a  little  iron  (5  to  15  per 


cent  FeO,  rarely  more). 
tonolite  (p.  269). 


Compare  HOT- 


CHRYSOLITE. 

(Olivine,  Peridot.) 


Prolectite. 

To  the  filtrate  ttdd  Give  a  little  water  when  intensely  ignited  in  a! 

to    precipitate    the,     ciosed    tube.      Generally    give    reactions    for  Chondrodite. 

fluorine  (p.  76,   §2)  and  iron.     These  closely 

related  minerals  must  be  distinguished  by 
differences  in  crystallization,  or  by  means  of 
a  quantitative  chemical  analysis. 


Humite. 


Jlinohumite. 


Contain  aluminium.  —  When 
treated  as  directed  in  the  fore- 
going paragraph  ammonia  pro- 
duces a  precipitate  of  alumin- 
ium hydroxide.  Distinguish- 
ed by  their  specific  gravity 
from  the  heavier  minerals  iu 
the  following  section. 


Crumbles    when    heated    B.    B.     Yields   much 
water  when  heated  in  a  closed  tube. 


Allophane. 


Gives  little  or  no  water   in  the    closed    tube. 
Fus.  =  5. 


Gehlenite. 


Essentially  a  thorium  silicate.     The  water  is  sup-  Thorite. 

(Granite.) 


Contain  the  rare-earth  metals.— •'     Posed  to  be  tbe  result  of  alteration. 

After  separation  of  the  silica  Contains  the  metals  of  the  cerium  group.     On  in- 
tense ignition  in  the  closed  tube  gives  a  little  Ceriie. 
water  (hydroxyl). 


the  solution  gives  the  reactions 
described  on  pp.  65  and  66. — 


The  high   specific   gravity  of  Contains 
these  minerals  is  noticeable. 


the  metals  of  the  yttrium  group. 
B.  B.  swells,  cracks  apart,  and  often  glows. 
Gives  little  or  no  water  in  the  closed  tube. 


Gadolinite. 


Contains  uranium. — Gives  with 
the  salt  of  phosphorus  bead  in 
O.  F.  a  yellowish-green  and 
in  R.  F.  a  green  color. 


Gives  water  in  the  closed  tube. 


Uranophane. 


METALLIC   LUSTER.  29* 

ifficultly  Fusible. 
yield  gelatinous  silica  upon  evaporation. 

e  finely  powdered  material  in  a  test-tube  with  from  3  to  5  cc.  of  hydrochloric  acid  and  boil  until 
n  the  volume  becomes  small  the  contents  of  the  tube  should  thicken,  owing  to  the  separation  of 
with  additional  water  or  acid. 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specffic 
Gravity. 

Crystalli- 
zation. 

2SiO4. 

Colorless, 
white,  green, 
yellow,  blue. 

Vitreous. 

C.  Basal,  & 
prismatic. 
F.  Uneven. 

5.5 

4.0-4.1 

Hex.  Rh. 
Page  196. 

i.OH)2SiO3. 

White,  pale- 
green  or  blue. 

Vitreous. 

J.  Prism.,  per. 
F.  Uneven. 

4.5-5 

3.45 

Orthorh. 
Piige  207. 

R2S)(SiO4)3. 

=  Zn.  Be  &  Fe. 

Pale  rose-red 
to  brownish. 

Vitreous, 
resinous. 

F.  Uneven. 

3.64 

Isom.  Tet. 

CuSiO<. 

Emerald-green 

Vitreous. 

J.  Rhomb.,  per. 
F.  Conchoidal. 

5 

3.35 

Hex.  Rh. 

Page  196. 

r2Si04. 

White,  gray, 
yellowish- 
white. 

Vitreous. 

3.  Pinacoidal. 
F.  Uneven. 

6.5-7 

3.24 

Orthorh. 

g.Fe)2Si04. 

Olive-  to 
grayish-green, 
brown. 

Vitreous. 

3.  Pinacoidal. 
F.  Uneven. 

6.5-7 

3.27- 

3.37 

Orthorh. 
Page  204. 

r[Mg(F,OH)]aSi04. 

Brownish-gray 

F.  Uneven. 

MODOCl. 

r,[Mg(F,OH)]a(SiO«),. 

Brownish-red, 
yellow,  white. 

Vitreous. 

C.  Basal. 
F.  Uneven. 

6-6.5 

3.15- 
3.25 

Monocl. 

r6[Mg(F,OH)]2(Si04)3. 

Brownish-red, 
yellow,  white. 

Vitreous. 

C.  Basal. 
F.  Uneven. 

6-6.5 

3.18- 
3.25 

Orthorh. 

r,[Mg(F,OH)],(Si04)4. 

Brownish  -red, 
yellow,  white. 

Vitreous. 

C.  Basal. 
F.  Uneven. 

6-6.5 

3.18- 
3.25 

Monocl. 

aSiO6.5Ha(X 

Colorless, 
yellow,  green, 
blue. 

Vitreous, 
wax-like. 

F.  Conchoidal. 

3 

1.88 

Amorph. 

a,Mg,Fe)3Al2Si2O10. 

Grayish-green 
to  brown. 

Vitreous, 
resinous. 

F.  Uneven. 

5.5-6 

2.9-3.0 

Tet  rag. 

iSiO4,  containing  water. 

Orange-yell'w, 

brown,  black. 

Resinous, 
greasy. 

C.  Prismatic. 
F.  Uneven. 

4.5-5 

4.8-5.2 

Tet  rag. 

;i,Fe)iCc())(Ce2.8OH) 
(SiO,),. 

&  Di  iso.  w.  Ce. 

Clove  brown, 
gray,  red. 

Dull, 
resinous. 

F.  Splintery, 
uneven. 

5.5 

4.85-4.9 

Orthorh. 
U.  mass. 

iBCaYaSisOjo. 

Black, 
greenish- 
black,  brown. 

Vitreous, 
greasy. 

F.  Conchoidal, 
splintery. 

6.5-7 

4.2-4.5 

Monocl. 

lUaSiaOn.SHaO. 

Honey-,  lemon- 
or  straw- 
yellow. 

Vitreous, 
silky. 

2-3 

3.8-3.9 

Triclinic. 
U.  acic. 

(Page  295.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER 

C. -Infusible  or  Very  Difficultly  Fusible. 

DIVISION  4. — Decomposed  by  hydrochloric  acid  with  the  separation  of  silica,  but  without 

the  formation  of  a  jelly. 


295 


II.    MINERALS   WITHO 


C.— Infusible  or  Ve 
DIVISION  4. — Decomposed  by  hydrochloric  acid  with  tin 

In  order  to  determine  that  a  mineral  belongs  in  this  division  treat  one  or  two  ivory-spoonfuls  o 
less  than  1  cc.  of  acid  remains.     The  behavior  during  this  treatment  should  be  carefully  observed. 
to  the  fine,  suspended  material;  when  boiled,  however,  the  liquid  becomes  translucent,  although  th 
decide  from  appearances  whether  the  insoluble  material  is  separated  silica  or  the  un decomposed  min 
to  oxidize  any  iron  that  may  be  present,  dilute  with  5  cc.  of  water,  boil,  and  filter,  when,  if  decom 
•will  precipitate  aluminium  and  iron,  which  may  be  filtered  off.     In  the  strongly  ammoniacal  filtrat 
while  if  other  bases  are  present  (sodium,  potassium,  and  lithium  excepted)  one  or  the  other  of  the 
for  testing  for  the  bases  see  p.  110,  §  4.  There  are  some  minerals  which  are  slowly  attacked  by  acids 
carbonate,  and  sodium  phosphate  ;  the  minerals  in  this  division,  however,  are  readily  decomposed  lr 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

Contains  copper.  —  Gives  a  glob- 
ule of  copper  when  a  little 
of  the  mineral  is  heated  with 
Na.jCOa  on  charcoal. 

In  the  closed  tube  darkens  and  gives  water. 

Chrysocolla. 

Contains  nickel.  —  Colors  the  bo- 
rax bead  in  O.  F.  violet  when 
hot  and  brown  when  cold. 

In  the  closed  tube  blackens  and  gives  water. 

Genthite. 

(Garnierite.) 

Contains  iron.  —  B.  B.  becomes 
black  and  magnetic. 

Give  water  in  the  closed  tube.  The  iron  is 
mostly  ferric  (p.  65,  §4). 

Hisingerite. 

Chloropal. 

Contain  magnesium.  —  The  HC1 
solution,  if  sufficiently  dilute, 
gives  no  or  only  a  slight  pre- 
cipitate with  ammonia  and 
ammonium  carbonate,  but 
gives  an  abundant  precipitate 
with  sodium  phosphate  (p.  91, 
§  1,  &).  &°  Compare  Clion- 
drodite  (p.  294). 

Commonly  in  compact,  greenish  masses.  Some- 
times fibrous  (Chrysotile,  Fig.  360,  p.  221)  or 
foliated  (Marmolite). 

SERPENTINE. 

((.,'hrysotile,       Se 
pen  tine  -  asbestu: 
Marmolite.) 

Somewhat  resembles  a  gum. 

Deweylite. 

(Gymnite.) 

Compact,  with  fine  earthy  texture.     Fus.  =  5. 

Sepiolite. 
(Meerschaum.) 

Contain   aluminium.  —  The  HC1 
solution    gives    an    abundant 
precipitate     with      a?nmouia. 
Distinguished  by  their  physi 
cal  properties  from  the  miner- 
als in  the  following  section. 

Generally  found  in  trapezohedrons  (Fig.  105, 
p.  171)  in  lava.  Reacts  for  potassium  (p.  105, 
§  1,  «)- 

LEUCITE.' 

The  HC1  solution,  filtered  from  the  silica,  gives 
with  hydrochlorplatinic  acid  a  cream-colored 
precipitate  (cwium,  p.  58). 

Pollucite. 

Contain  the  rare  earth  metals.— 
After  separation  of  the  silica 
the  solution  gives  the  reactions 
described  on  pp.  65  and  66. 

Color  the  flame  green  when  fused  with  the 
potassium  bisulphate  and  fluorite  mixture 
(boron,  p.  56,  §  1). 

Melanocerite. 

Caryocerite. 

METALLIC    LUSTER.  295 

Difficultly  Fusible. 

iration  of  silica,  but  without  the  formation  of  a  jelly. 

finely  powdered  material  in  a  test-tube  with  from  3  to  5  cc.  of  hyurochloric  acid  and  boil  until 
en  the  powder  is  first  shaken  up  with  the  cold  acid  the  liquid  will  generally  appear  milky,  owing 
)arated  silica  prevents  it  from  becoming  perfectly  clear.  After  a  little  experience  one  can  usually 
;  in  order  to  decide  definitely,  however,  proceed  as  follows  :  Add  a  drop  of  nitric  acid  in  order 
ion  has  taken  place,  the  bases  will  be  in  the  filtrate.  Ammonia,  added  in  excess  to  the  solution, 
monium  carbonate  and  sodium  phosphate  will  precipitate  calcium  and  magnesium,  respectively, 
ints  previously  mentioned  will  be  very  sure  to  produce  a  precipitate.  For  more  complete  details 
give,  consequently,  slight  precipitates  of  the  bases  when  tests  are  made  with,  ammonia,  ammonium 
Is. 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 

ness. 

Specific 
Gravity. 

Crystalli- 
zation . 

Si03.2H20? 

Mountain- 
green  to 
turquois-blue. 

Vitreous, 
earthy. 

F.  Uneven. 

2-4 

2.0-2.4 

Massive. 
Earthy. 

Ni2Mg2(Si04)3.4HaO? 

Pale-  to  deep- 
green. 

Dull  to 
resinous. 

F.  Uneven. 

3-4 

2.2-2.8 

Amorph. 
Botryoid. 

certain. 

O  Fe"',Fe",Ms,H2O. 

Black  to 
brown-black. 

Pitch-like, 
vitreous. 

F.  Conchoidal. 

3 

2.5-3.0 

Amorph. 

Fe2(SiO4)3.2H2O? 

Greenish-yel- 
low, pistachio- 
green. 

Wax-like. 

F.  Couchoidal, 
splintery. 

2.5-4.5 

1.7-1.9 

Compact. 
Amorph. 

(Mg,Fe)3Si2O9. 

Olive  to 
blackish-green, 
yellowish- 
green,  white. 

Greasy, 
wax-  like. 

F.  Uneven, 
splintery. 

2.5-5. 

U.4 

2.5-2.65 

Massive. 
Pseudo- 
morphous 
(p.  220). 

Mg4(Si04)3.4H20. 
iso.  w.  Mg:. 

Yellow  to 
apple-green. 

Resinous. 

F.  Uneven, 
conchoidal. 

3-4 

2.40 

Amorph. 

MgaSi3010. 

White  to 
grayish-  white. 

Dull. 

F.  Uneven. 

2-2.5 

2.0 

Compact. 
Earthy. 

A.l(Si03)2. 

iso.  w.  K. 

White,  gray, 
colorless. 

Vitreous. 

F.  Uneven, 
conchoidal. 

5.5-6 

2.45- 
2.50 

Isometric. 
U.  cryst. 

.Cs4Al4(SiO3)8. 

Colorless, 
white. 

Vitreous. 

F.  Conchoidal. 

6.5 

2.98 

Isometric. 
U.  mass: 

icertain. 
,  Ta,  B,  Ce,  La,  Di,  Y, 
Ca,  Na,  H,  F. 

Deep-brown  to 
black. 

Greasy, 
vitreous. 

F.  Conchoidal. 

5-6 

4.13 

Hex.  Rh. 

u  certain. 
,  Tii,  B.  Th,  Ce,  La, 
Di,  Y,  Ca,  Na,  H,  F. 

Nut-brown. 

Greasy, 
vitreous. 

F.  Conchoidal. 

5-6 

4.29 

Hex.  Rh. 

(Page  296.) 

II.  MINERALS  WITHOUT   METALLIC   LUSTER. 

C.— Infusible  or  Very  Difficultly  Fusible. 

DIVISION  5. — Not  belonging  to  the  foregoing  divisions. — Insoluble  in  hydrochloric  acid, 
or  only  slightly  acted  upon. 

Section  a. — Hardness  less  than  that  of  glass  or  a  good  quality  of  steel. — Can  be  scratched 

by  a  knife.—  In  part. 


II.   MINERALS   WITHOT 
C. — Infusible  or  Ver 

DIVISION  5. — Not  belonging  to  the  foregoing  divisions. — . 
Section  a. — Hardness  less  than  that  of  glass  or  a  gc 


General  Characters. 

Specific  Characters. 

Name  of  Species. 

Iron  Ores.  —  B.B.  in  li.P.  become 
strongly  magnetic. 

Compare  the  difficultly  soluble  oxides  and  hy- 
droxides of  iron  on  p.  292. 

IRON   ORES. 

(See  p.  292.) 

Structure  foliated  or  micaceous.  — 
Folias  tough  and  elastic. 

THE  MICAS.—  Difficultly  fusible. 

MICAS. 

(For   varieties  see 
p.  284.) 

Structure  foliated  or  micaceous.— 
Folise  tough  and  flexible,  but 
not  elastic.  JSg"  Compare  Talc, 
beyond. 

On  intense  ignition  B.  B.  in  the  closed  tube  give 
considerable  water.  See  p.  284. 

CLINOCHLORE.* 

(Chlorite,    Ripido- 
lite.) 

Color  reddish.  —  Reacts  like  the  foregoing,  but 
imparts  to  the  borax  bead  in  R.  F.  a  green 
color  (chromium}. 

KSmmererite. 
(Chrom-clinochlore.) 

B.  B.  becomes  black  and  magnetic. 

Prochlorite. 

Structure  fol 

TJWlifn   XiW 

'ated  or  micaceous. 
ttte  (Brittle  Micas.) 

Distinguished  by  differences  in  color. 

Seybertite. 

(Clintonite.) 

Xanthophyllite. 

Very  soft,   and    have    a   greasy 
feel.—  Give    a    little  water  (5 
per  cent)  on  intense  ignition 
in  a  closed  tube. 
t^~  Compare  Kaolinite,  beyond. 

Ignited,  then  moistened  with  cobalt  nitrate  and 
again  ignited  assumes  a  blue  color  (aluminium). 
Often  exfoliate  prodigiously  when  heated  B.  B. 

PYROPHYLLITE. 

(Agalmatolite.) 

Does  not  give  the  foregoing  reaction  for  alumin- 
ium. 

TALC. 

(Steatite,  Soapstone.) 

Sulphates.—  Give    strongly    acid 
water  and  the  odor  of  sulphur 
dioxide,  when  intensely  heated 
'in  a  closed  glass  tube. 

Ignited,  then  moistened  with  cobalt  nitrate  and 
again  ignited,  assume  a  blue  color  (aluminium). 
Alunite  must  be  heated  nearly  to  redness  be- 
fore it  gives  water.  Lowigite  parts  with  some 
of  its  water  at  a  low  temperature. 

Alunite. 

Lowigite. 

—  Decompose  by  fusion  with  Na2CO3, 
d  on  p.  110,  §  4,  then  dissolve  in  HNO3 
he  solution  by  adding  a  few  drops  of  it 
uium  molybdate  (p.  102,  §  1).  The 
sh-greeii  flame  will  often  serve  to  in- 
)hosphate(p.  102,  §2). 

Contain  the  rare-earth  metals.  —  Decompose  an  ivory-spoonful  of  the 
finely  powdered  mineral  by  heating  in  a  test-tube  with  from  4  to  6 
drops  of  concentrated  H2SO4.     After  cooling,  dilute  witli  10  cc.  of 
water,  filter  if  necessary,  and  add  ammonium  oxalate,  when  a  pre- 
cipitate of  the  rare-earth  metals  will  be  formed  (pp.  65  aud  06). 

Monazite. 

Xenotime. 

Contain  calcium.  —  Decompose  by  fusion  with  Na2CO3,  as  directed 
on  p.  110,  §4,  and  dissolve  in  *HC1  or  HNO3.     Add  ammonia  to 
the  solution  until  a  precipitate  forms,  then  HC1,  a  drop  at  a  time, 
until  the  liquid  becomes  clear,  dilute  to  a  volume  of  10  cc.   and 
add  ammonium  oxalate,  which  will  precipitate  calcium  oxalate  (p. 
60,  §  6).     Svanbergite  reacts  for  a  sulphate  (p.  122,  §  1). 

Tavistockite. 

Goyazite. 

Svanbergite. 

Contain  aluminium.  —  Ignited,  then  moistened  with  cobalt  nitrate 
and  again  ignited,  assume  a  blue  color.     Wavellite  is  usually  in 
radiated,  hemispherical  or  globular  aggregates. 
H5iP~  Compare   the   phosphates  on   p.  298,  some  of  which  are  un- 
doubtedly difficultly  soluble  or  insoluble  in  HC1. 

Wavellite. 

Augelite. 

*Ili|- 

S  23  S^5 

1^-TS   ~   ®   g 

Isisas 

&H 

Variscite. 

Color  blue.     B.  B.  swells,  loses  its  color  and  falls  to  pieces. 

Lazulite. 

DIVISION  6  Section  a.— Continued  on  next  page. 


*  Amesite,  Penninite,  Corundophilite  and  other  folia 


METALLIC   LUSTER. 

ifficultly  Fusible. 

uble  in  hydrochloric  acid,  or  only  slightly  acted  upon. 

lality  of  steel.— Can  be  scratched  by  a  knife. 


295 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Crystalli- 
zation. 

es  and  hydroxides  of 
on. 

:ates  of 
H,  K,  Mg,  Fe  &  Al. 

White,  yellow, 
brown,  green, 
black. 

Vitreous, 
pearly. 

C.  Basal, 
eminent. 

3-3 

2.8-3.0 

Monoci. 

[g6Al2Si3018. 

o.  w.  Mg  &  Al. 

Green  of  va- 
rious shades, 
rarely  white. 

Vitreous, 
pearly. 

C.  Basal,  per. 

2-2.5 

2.65- 
2.75 

Monoeiu 

[g»(Al,Cr)3SisO18. 

Garnet  to 
peach-blossom- 
red. 

Vitreous, 
pearly. 

C.  Basal  ,  per. 

2-2.5 

2.65- 
2.75 

Monoci. 

Fe,Mg)23Al14Si13O90? 

Green  to 
blackish-green 

Vitreous, 
pearly. 

C.  Basal,  per. 

1-2 

2.78- 
2.95 

Monoci 

Hg,Ca)6AUSi2O18. 

Reddish- 
brown,  copper- 
red. 

Pearly. 

0.  Basal,  per. 
F.  Uneven. 

4-5 

3.0-3.1 

Monoci 

Ig,Ca)i4Al16Si6O52. 

Light-green. 

Vitreous, 
pearly. 

C.  Basal,  per. 

4-5 

3.0-3.1 

Monoci 

l,(SiO,)4. 

White,  apple- 
green,  gray, 
brown. 

Pearly. 

C.  Basal,  per. 

1-2 

2.8-2.9 

Foliated 
Compact 

:g3(Sio3)4. 

Apple-green, 
gray,  white. 

Pearly, 
greasy. 

C.  Basal,  per. 

1 

2.80 

Foliated 
Compact 

Ta)(A1.20H)3(S04)2. 

White,  gray. 

Vitreous. 

C.  Basal. 
F.  Uneven. 

3.5-4 

2,83 

Hex.  Kb. 
U.  tabui. 

1.30H),(S04),.14H10. 

Straw-yellow. 

Vitreous. 

F.  Conchoidal. 

8-4 

2.58 

Massive 

ja,Di)PO4,  of  ten  with 
iSiO4. 

Yellowish-  to 
reddish-brown, 

Resinous. 

Parting  basal. 
B\  Uneven. 

5-5.5 

5.2-5.3 

Monoci. 

4- 

Er  iso.  w.  Y. 

Yellowish-  to 
reddish-brown 

Resinous, 
vitreous. 

C.  Prism.,  per. 
F.  Uneven. 

4-5 

4.55-5.1 

Tetrag 

Ll2(OH)6(P04)2. 

White. 

Pearly. 

Acicular. 

.l,oP2O2S.9H2O. 

Yellowish- 
white. 

C.  Basal. 

5 

3.26 

Hexag.  or 
tetrag. 

irtain. 
),(P04),Al,Ca,H20. 

Yellow,brown, 
rose-  red. 

Vitreous. 

C.  Basal,  per. 

5 

3.3-3.5 

Hex.  Rh. 

)H)3(P04)2.5H20. 
w.  OH. 

White,  yellow, 
green,  brown. 

Vitreous, 
pearly. 

3.  Pinacoidal. 
F.  Uneven. 

3-4 

2.33 

Orthorh. 

)H)3P04. 

Colortess, 
white. 

Vitreous, 
pearly. 

3.  Prism.,  per. 
F.  Uneven. 

4.5-5 

2.70 

Monoci. 

)4.2H20. 

Colorless, 
apple-  to 
emerald-green. 

Vitreous. 

4 

2.4 

Orthorh. 
U.  mass. 

Fe)(A1.0H)a(P04)2. 

Azure-blue. 

Vitreous. 

C.  Prismatic. 
F.  Uneven. 

5-5.5 

3.05-3.1 

Monoci. 

uerals  of  the  chlorite  group  are  here  included. 


(Page  297.) 

II.  MINERALS   WITHOUT   METALLIC  LUSTER. 

C.— Infusible  or  Very  Difficultly  Fusible. 

DIVISION  5. — Insoluble  in  hydrochloric  acid,  or  only  slightly  acted  upon. 

Section  a. — Hardness  less  than  that  of  glass  or  a  good  quality  of  steel. — Can  be  scratched 

by  a  knife. — Continued. 


297 


II.   MINERALS   WITH( 

C.— Infusible  or  V 

DIVISION  5. — Insoluble  in  hydrochloric,  a 

Section  a,  —Hardness  less  tfian  that  of  glass  or  a  good  i 


General  Characters. 

Specific  Characters. 

Name  of  Species 

Contain  fluorine  and  water.— 
When  intensely  heated  in  a 
closed  glass  tube  yield  acid 
water,  and  vapors  which  cor- 
rode the  glass  (p.  77,  §5). 

Crystallizes  in  octahedrons. 

Ralston  ite. 

Crystallizes  in  pyramids. 

Fluellite. 

B.  B.  whitens  and  shows  slight  indication  of 
fusion.  Gives  with  turmeric-paper  a  faint 
alkaline  reaction. 

Prosopite. 

Contain  fluorine  and  but  little  or 
no  water.  —  Give  a  deposit  of 
silica  when  fused  with  potas- 
sium  bisulphate  in  a   closed 
tube  of  6  mm.  internal  diam- 
eter (p.  76,  §  2). 

Heat  the  finely  powdered  mineral  in  a  test-tube 
with  from  4-6  drops  of  concentrated  H2SO4. 
After  cooling,  add  10  cc.  of  water  and  test  for 
the  rare-earth  metals  with  ammonium  oxalate 
(p.  65).  Bastnasite  effervesces  slightly  with 

Tysonite. 

Bastnasite. 

Contain  aluminium.  —  Assume  a 
blue  color  when  moistened 
with  cobalt  nitrate  and  ignited 
B  B.,  but  do  not  give  the  re- 
actions of  the  preceding  divi- 
sions. 

/ 

Gives  little  or  no  water  in  the  closed  tube,  while 
the  others  give  waier. 

CYANITE. 

(Disthene.) 

Generally  clay-like,  compact  or  mealy.  Gives 
a  skeleton  of  silica  in  the  salt  of  phosphorus 
bead  (p.  112,  §5). 

KAOLINITE.* 

(Porcelain  Clay.) 

Wholly  soluble  in  the  salt  of  phosphorus  bead 
(absence  of  silica).     Hydrargillite  occurs  gen- 
erally as  an  incrustation  or   stalactitic,  rarely 
,    crystallized;  Bauxite  generally  in  rounded  or 
concretionary  grains. 

Hydrargillite. 

(Gibbsite.) 

Bauxite. 
(Aluminium  Ore. 

Contains  nickel.  —  Imparts  to  the 
borax  bead  in  O.  F.  a  violet 
color  when  hot,  brown  when 
cold. 

In  the  closed  tube  blackens  and  gives  water  (see 
p.  295). 

Genthite. 

(Garnierite.) 

Contain    antimony.  —  Give    glob- 
ules of  the  metal  and  a  coating 
of  its   oxide  when   heated   in 
R.   F.  with  Na3CO3  on  char- 
coal. 
B5F"   Compare  Lewisite,   Manze- 
liite  and  other  antimony  min- 
erals on  p.  263,  and  Atopite,  p. 
298. 

Gives  water  in  the  closed  tube. 

Stibiconite. 

Occurs  in  acicular  crystals  and  as  an  incrusta- 
tion. 

Cervantite. 

Becomes  magnetic  after  heating  B.  B. 

Tripuhyite. 

Characterized  by  containing  tantalum,  p.  123. 

Stibiotantalite. 

Contains  zinc.  —  Test  as  directed 
on  p.  131  (Fig.  49). 

Rather  slowly  acted  upon  by  hot  HC1,  with 
evolution  of  hydrogen  sulphide. 

SPHALERITE. 

See  p.  292. 

Contain    titanium.  —  Fused   with 
borax,  then   dissolved  in  HC1 
and   boiled  with  tin,  the  solu- 
tion   becomes  violet  (p.    127, 
§2). 
I3F"  Compare  Pyrochlore,    next 
page. 

When  fused  with  the  bisulphate  of  potash  and 
fluorite  mixture,  momentarily  colors  the  flame 
green  (boron,  p.  56,  £  1). 

WarVicki  te. 

After  precipitating  titanium  from  the  HC1  solu- 
tion with  amniouia  and  filtering,  the  filtrate 
will  react  for  calcium  with  ammonium  oxalate. 

Perovskite.      S<?e 
dysanalyte,  p.  257. 

Turmeric-paper  assumes  an  orange  color  when 
placed  in  the  HC1  solution  (zirconium,  p.  133). 

Zirkelite. 

*  Halloysite,  Newtonite,  Cimolite,  Montmorillinite,  Collyrite  aud  Schrotterite  are  closely  related  Kaol 
DIVISION  5,  Section  a. — Concluded  on  next  page. 


T   METALLIC   LUSTER. 

Difficultly  Fusible. 

or  only  slightly  acted  upon. — Continued. 

ity  of  steel.— Can  be  scratched  by  a  knife.—  Continued. 


297 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Crystalli- 
zation. 

Na2,Mg)Fa.3Al(F,OH),. 
2HaO. 

White  to  straw- 
yellow. 

Vitreous. 

F.  Uneven. 

4.5 

2.58 

Isometric. 

i!F3.HaO. 

Colorless, 
white. 

Vitreous. 

F.  Uneven. 

3 

2.17 

Orthorh. 

>(F,OH)3.2A1(F,OH),. 

Colorless, 
white,  gray. 

Vitreous. 

C.  Prismatic. 
F.  Uneven. 

4.5 

2.89 

Monocl. 

Ce,La,Di)F,. 

Wax-yellow  to 
reddish-  brown. 

Vitreous, 
resinous. 

C.  Basal,  per. 
F.  Uneven. 

4.5-5 

6.13 

Hexag. 

RF>CO,. 
I  =  Ce,  La  &  Di. 

Wax-yellow  to 
reddish-brown. 

Vitreous, 
greasy. 

F.  Conchoidal. 

4-4.5 

4.9-5.2 

Massive. 

Triclinic. 
Page  217. 

^.l2SiO6. 

Bine,  green, 
gray  or  white. 

Vitreous, 
.    pearly. 

C.  Pinacoidal, 
pe.rftct. 

5-7 
(p.  302.) 

3.56 
-3.66 

I4AliSiaO9. 

White. 

Pearly,  dull. 

C.  Basal,  per. 
F.  Earthy. 

2-2.5 

2.6-2.63 

Monocl. 

L1(OH)3. 

White. 

Pearly, 
vitreous,  dull. 

C.  Basal. 

2.5-3.5 

2.3-2.4 

Monocl. 

U20(OH)4. 

White,  gray, 
yellow,  red. 

Dull,  earthy. 

2.55 

Massive. 
Clay-like. 

I4NiaMga(Si04),.4H,0? 

Pale-  to  deep- 
green. 

Dull  to 
resinous. 

F.  Uneven. 

3-4 

2.2-2.8 

Amorph. 
Botryoid. 

>b3O4.H3O. 

Pale  yellow  to 
yellowish- 
white. 

Pearly, 
earthy. 

4-4.5 

5.1-5.3 

Massive. 
Compact. 

;bao<. 

\V  hite  to 
yellow. 

Greasy, 
pearly. 

4-5 

4.08 

Orthorh.? 
Acicular. 

^e2Sb2O7? 

Greenish- 
yellow. 

Resinous. 

5.82 

Massive. 

;b(Ta,Nb)O4. 

Pale-reddish- 

to  greenish- 
yellow. 

Adamantine. 

Conchoidal. 

5 

6.5-7.4 

Orthorh.? 

IsomTTet. 
Page  175. 

IuS. 

"e  and  rarely  Cd  iso.  w.  Zn. 

Brown,  yellow, 
green,  white. 

Resinous, 
adamantine. 

C.  Dodecabe- 
dral,  perfect. 

3.5-4 

4.10 

Mg,Fe)4TiBaO«? 

Hair-brown, 
dull-black. 

Vitreous,  dull. 

C.  Piuac.,  per. 
F.  Uneven. 

3-4 

3.36 

Orthorh. 

)aTiO8. 

Yellow, 
orange,  brown, 
black. 

Adamantine. 

C.  Cubic. 
F.  Uneven. 

5.5 

4.03 

Isometric, 

Ca,Fe,UOa)(Zr,Ti)2O5.      jBlack. 

Resinous. 

F.  Conchoidal. 

5            I  4.71 

Isometric. 

ke  minerals,  with  varying  proportions  of  water,  and,  in  some  cases,  of  uncertain  chemical  composition. 


(Page  298.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

C.—  Infusible  or  Very  Difficultly  Fusible. 
DIVISION  5. — Insoluble  in  hydrochloric  acid,  or  only  slightly  acted  upon. 

Section  a.— Hardness  less  than  that  of  glass  or  a  good  quality  of  steel.—  Can  be  scratched 
by  a  knife.— Concluded. 

Section  b.— Hardness  equal  to  or  greater  than  that  of  glass.—  Can  not  be  scratched  by  a 
knife. — In  part. 


(Page  299.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

C.— Infusible  or  Very  Difficultly  Fusible. 
DIVISION  5.—I?isoluble  in  hydrochloric  acid,  or  only  slightly  acted  upon. 

Section  b.— Hardness  equal  to  or  greater  than  that  of  glass.—  Can  not  be  scratched  by  a 

knife. — Continued. 


299 


II.   MINERALS   WITIIO 

C.— Infusible  or  V( 

DIVISION  5. — Insoluble  in  hydrochloric  ac 

Section  6. — Hardness  equal  to  or  greater  than  that  oj 


General  Characters. 

Specific  Characters. 

Name  of  Species 

Leave   aD    insoluble   skeleton  of 
silica  when  the  finely  pulver- 
ized minerals  are  fused  B.  B. 
in  the  salt  of  phosphorus  bead 
(p.  112,  §  5). 

Imparts  a  green  color  to  the  salt  of  phosphorus 
bead  (chromium). 

Uvarovite. 
(Calcium-chromiu 
Garnet.) 

B.  B.  turns  black.  Reacts  for  sulphur  (p.  122, 
§2). 

Melauophlogite. 

Gives  strongly  acid  water  in  the  closed  tube. 
Assumes  a  blue  color  when  ignited  with  cobalt 
nitrate  (aluminium). 

Zunyite. 

Gives  globules  of  tin  when  fused 
B.      B.     on     charcoal     with  The  high  specific  gravity  is  noticeable. 
NaaCOs  and  charcoal  powder  (CUP  Compare  Nordenskioldinet  beyond, 
(p.  125,  §1). 

CASSITERITE. 

(Tin  Stone.) 

Fused  with   NaaCO3,  then  dis- 
solved in  HC1  and  boiled  with 
tin,    the    solution    assumes    a 
violet  color  (titanium,  p.  127, 
§  2).     E3^~  Rutile,  octahedrite, 
and  brookite  (p.  300)  furnish 
an   interesting  illustration  of 
trimorphism. 

Usually  in  prismatic  crystals,  often  very  slender 
and  twinned. 

RUTILE. 

Distinguished  from  the  foregoing  by  the  habit 
of  its  crystals  and  by  its  different  physical 
properties. 

Octahedrite. 
(Anatase.) 

Fuse  B.  B.  in  a  Na2CO3  bead 
and  dissolve  in  1  cc.  HC1  and 
1  cc.  of  water.      A  turmeric- 
paper  placed  in  this  solution 
assumes  an  orange  color  (zir- 
conium, p.  133). 

A  small  fragment  when  intensely  heated  B.  B. 
glows  and  emits  a  white  light. 
B3F"  Compare  Baddeleyite  (p.  302). 

ZIRCON. 

(Hyacinth.) 

Fused  B.  B.  with  borax,   then 
dissolved  in  HC1  and   boiled 
with  tin,  the  solution  assumes 
a  blue  color  (niobium,  p.  90, 
§1). 

Fergusonite  is  essentially  a  niobate  of  yttrium, 
and  sipylite  a  niobate  of  erbium. 
E3F"  Compare  the  niobates  (p.  300). 

Fergusonite. 

Sipylite. 

•Characterized  by  extreme  hard- 
ness. —  The    transparent,    col- 
ored varieties  are  highly  prized 
as  gem  materials. 

The  finely  pulverized  mineral  when  made  into  a 
paste  with  cobalt  nitrate  and  intensely  heated 
B.  B.  on  charcoal  assumes  &  blue  color  (alumin- 
ium). 

CORUNDUM. 

(Sapphire        wh 
blue,    Ruby    wb 
red,  Emery.) 

"°  B.  unaltered.     Yields  a  clear 
glass  w  lien  the  finely  pulverized 
mineral  is  mixed  with  an  equal 
volume  of  Na3COs  (rather  less 
Na.,COs    than    more),    and    a 
little  of  this  mixture  is  fused 
B.  B.  in  a  small  loop  on  plat- 
inum    wire.  —  Give    no    reac- 
tions for  the  bases  when  tested 
as  directed  on  p.  110,  §4. 
t3T"   Jompnre    Chalcedony    and 
Opal  (p.  302). 

Crystallized  generally  in  hexagonal  prisms,  ter- 
minated by  rhombohedrons  (p.  197). 
Amethyst  is  violet.     Agate  is  compact,  clouded, 
banded,    and    variously   colored.       Jasper  is 
colored  red  or  brown  by  hematite  or  lirnonite. 
Chert  and  Flint  are  compact,  and  vary  in  color 
from  white  or  gray  to  black. 

QUARTZ. 

(Rock  Crystal, 
Amethyst,    Aga 
Jasper,  Chert, 
Flint.) 

Crystals  are  generally  thin  hexagonal  plates, 
often  twinned. 

Tridymite. 

DIVISION  5,  Section  &.— Continued  on  next  page. 


1   METALLIC   LUSTEK. 

Difficultly  Fusible. 
or  only  slightly  acted  upon. — Continued. 
ss. — Can  not  be  scratched  by  a  knife. — Continued. 


Con  .position. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Crystalli- 
zation. 

Ja,Cr,(8iO.),. 

U  iso.  w.  Cr. 

Emerald-green 

Vitreous. 

F.  Conchoidal. 

7.5 

3.4-3.5 

Isometric* 
Fig.  97. 

Jncertain.                             Colorless  to 
SiO2  with  SO3  and  H2O.         light-brown. 

Vitreous. 

6.5-7 

2.02 

Isometric. 
Cubes. 

A1.2(OH,F,C1)]6A12           Colorless, 
(SiO4)s.l     white,  gray. 

Vitreous. 

F.  Uneven. 

7 

2.88 

Isom.Tet* 
Tetrahe- 
drons. 

Brown  to 
„  A                                          black. 
>DUt*                                 .  !  Rarely  yellow 
or  white. 

Adamantine. 

F.  Uneven. 

6-7 

6.8-7.1 

Tetrag. 
Page  180. 

no,. 

Yellow, 
reddish-brown 
to  black. 

Adamantine. 

C.  Prismatic. 
F.  Uneven. 

6-6.5 

4.18- 
4.25 

Tetrag. 
Page  18L 

no,. 

Yellow, 
brown,  blue, 
black. 

Adamantine. 

C.  Basal  and 
pyramidal. 
F.  Conchoidal. 

5.5-6 

3.8-3.95 

Tetrag. 
Page  181. 

5rSiO4. 

Colorless, 
gray,  green, 
brown,  red. 

Adamantine. 

C.  Prismatic. 
F.  Conchoidal. 

7.5 

4.68 

Tetrag. 
Page  1801 

Y,Er,Ce)(Nb,T8)O». 

Brownish- 
black. 

Resinous, 
pitch-like. 

F.  Uneven. 

5.5-6 

4.3-5.8 

Tetrag.  • 
Cl.20,p.2l9» 
U.  mass. 

Er,  Ce,La,Di,Hs)NbO4? 

Brownish- 
black. 

Resinous. 

F.  Uneven. 

6 

4.9 

Tetrag. 
U.  mass. 

yso,. 

White,  gray, 
yellow,  brown, 
green,  blue, 
pink,  red. 

Adamantine, 
vitreous. 

Parting  basal 
and  rhoinbo- 
hedral. 
F.  Uneven. 

9 

3.95-4.1 

Hex.  Rh. 
Page  194. 

SiO,. 

Colorless, 
white,  smoky. 
Variously 
colored  when 
impure. 

Vitreous, 
greasy. 

C.  Rhoinbo- 
hedralj  in 
traces. 
F.  Conchoidal. 

7 

2.65- 
2.  60 

Hex.  Rh. 
Page  1'JT.. 

MOa. 

While, 
colorless. 

Vitreous. 

F.  Conchoidal. 

7 

2.28- 
2.83 

Hexag. 
Tubular. 

(Page  300.) 

II.  MINERALS  WITHOUT   METALLIC   LUSTER. 

C.— Infusible  or  Very  Difficultly  Fusible. 

DIVISION  5. — Insoluble  in  hydrochloric  acid,  or  only  slightly  acted  upon. 

Section  b. — Hardness  equal  to  or  greater  tlian  that  of  glass. — Can  not  be  scratched  by 

knife. — Contin  ued. 


300 


II.   MINERALS   WITHO 

C.— Infusible  or  V< 

DIVISION  5. — Insoluble  in  hydrocJiloric  ai 

Section  b. — Hardness  equal  to  or  greater  than  that  o 


General  Characters. 

Specific  Characters. 

Name  of  Species 

B.  B.  unaltered.  Does  not  give 
a  clear  glass  with  Na2CO3, 
when  treated  as  directed  in 
the  foregoing  paragraph. 

Reacts  for  beryllium  (p.  53,  §  a). 

Phenacite. 

B.  B.  become  milk-white,  and  at 
a  high  temperature  show  indi- 

Momentarily  colors  the  blowpipe  flame  green 
(boron),  when  heated  on  platinum  wire  with 
the  potassium  bisulphate  and  fluorite  mixture 
(p.  56,  §  1). 

TOURMALINE. 
(Achroite  when  c 
orless,       Indicol 
when   blue.  Rub 
lite  when  red.) 

Tourmaliue  exhibits  pyroelec- 
tricity  (p.  231). 

In  the  closed  tube  at  a  red  heat  unchanged,  but 
on  intense  ignition  B.  B,  whitens  and  yields 
about  2  per  cent  of  water. 

BERYL. 

(Aquamarine  wh 
pale  green,  Emt 
aid    when     brig 
green.) 

B.  B.  give  a  green  flame  (boron). 

Gives  globules  of  tin  when  fused  B.  B.  on  char- 
coal with  NaaCO3  and  charcoal  powder  (p. 
125,  §1). 

Nordenskioldine. 

Assumes  a  blue  color  when  ignited  with  cobalt 
nitrate  (aluminium). 

Jeremejevite. 

Nidbates.  —  Fused    with    borax, 
then    dissolved    in    HC1    and 
boiled  with  tin,   the  solution 
assumes  at  first  a  violet  color 
(titanium),  which  changes  on 
continued  boiling  to  blue  (ni- 
obium, p.  99,  §  1). 
Jgf  Compare  the  Niobates,  pp. 
254,  257,  298  and  299. 

Distinguished  with  difficulty,  and  often  only  by 
studying  the  habit  and  angles  of  the  crystals. 
Characterized    by    their    dark    color,    resinous 
(pitch-like)  luster  and  high  specific  gravity. 

^Eschynite. 

Kuxenite. 

Polycrase. 

Reacts  for  titanium,  but  not 
for  niobium  when  tested  as 
above. 

Usually  in  tabular  crystals. 
J£p~  Compare  Rutile  and  Octahedrite  (p.  299). 

Brookite. 

Usually  has  a  blue  color,  but  by 
transmitted  light  appears 
almost  white  when  viewed  in 
certain  directions. 

[n  the  closed  tube  at  a  red  heat  unchanged,  but 
on  intense  ignition  B.  B.  yields  about  1£  per 
cent  of  water. 

IOLITE. 

(Cordierite.) 

In  prismatic  crystals,  common- 
ly twinned  (p.  205).  Often 
very  impure. 

In  the  closed  tube  at  a  red  heat  unchanged,  but 
on  intense  ignition  B.  B.  yields  about  2  per 
cent  of  water. 

STAU  ROUTE. 

Reacts  for  boron  (p.  56,  §  2). 

Gives  water  in  the  closed  tube. 

Hambergite. 

Gives  a  reaction  for  fluorine  when 
heated  in  a  bulb  tube  with 
sodium  metaphosphate  (p.  76, 
§3). 

The  pulverized  mineral  when  moistened  with 
cobalt  nitrate  and  intensely  heated  B.  B.  on 
charcoal  assumes  a  blue  color  (aluminium). 

TOPAZ. 

DIVISION  5,  Section  b. — Continued  on  next  page. 


?  METALLIC   LUSTER. 
Difficultly  Fusible. 

or  only  slightly  acted  upon. — Continued. 

ass. — Can  not  be  scratched  by  a  knife. — Continued. 


300 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

CrrstaUi. 

zation. 

Je2SiO4. 

White, 
colorless. 

Vitreous. 

C.  Prismatic. 
F.  Conchoidal. 

7.5-8 

2.96 

Hex.  Rh. 
Page  196. 

r9Al3(B.OH),Si4O19. 
I'o  replaced  by 
U,  Fe",  Mg,  Mn,Ca,  Na, 
[,  Li  and  H.     F  iso.  w.  OH. 

Colorless, 
green,  blue, 
pink,  red. 

Vitreous. 

F.  Couchoidal, 
Uneven. 

7-7.5 

3.0-3.1 

Hex.  Rh- 
3e*mmoit» 
Page  195. 

Lpproximately 
BesAl2(SiOs)6.|HaO. 

Green,  yellow, 
blue,  pink, 
colorless. 

Vitreous. 

F.  Conchoidal, 
Uneven. 

7-7.5 

2.7-2.75 

Hexag. 
Page  188. 

JaSn(BO>)i. 

Sulphur-  to 
lemon-yellow. 

Pearly, 
vitreous. 

C.  Basal,  per. 
F.  Conchoidal. 

5.5-6 

4.20 

Hex.  Rh. 
Tabular. 

LlB03. 

Colorless  to 
pale  yellow. 

Vitreous. 

F.  Uneven. 

6.5 

3.28 

Hexag. 
Prism. 

Jncertain. 
Jb,  Ti,  Th,  Ce,  La,  Ca, 
Fe,  0. 

Brownish- 
black  to  black. 

Resinous. 

F.  Uneven, 
Conchoidal. 

6 

4.95- 
5.15 

Orthorh. 

Jncertain. 
Jb,Ti,  Y,Er,Ce,U,Fe,H,O. 

Brownish- 
i)lack  to  black. 

Resinous. 

F.  Uneven, 
Conchoidal. 

6.5 

4.6-5.0 

Orthorh. 
U.  mass. 

Jncertain. 
fb,  Ti,  Y,Er,Ce,U,Fe,H,O. 

Brownish- 
black  to  black. 

Resinous. 

F.  Conchoidal. 

6 

4.95- 
5.05 

Orthorh. 

ftO,. 

Hair-brown  to 
black. 

Adamantine. 

F.  Uneven. 

6 

40-4.08 

Orthorh, 

I,(Mg,Fe)4Al.Si,.OM. 

Light  or  dark 
blue. 
Seldom 
colorless. 

Vitreous. 

C.  Pinacoidal. 
F.  Conchoidal. 

7-7.5 

2.61 

Orthorh. 

AlO)4(Al.OH)Fe(SiO4),. 

"e  iso.  w.  Al;  Mg  iso.  w.  Fe. 

Red-brown  to 
brownish- 
black. 

Resinous, 
vitreous. 

C.  Pinacoidal. 
F.  Uneven. 

7-7.5 

3.75- 
3.78 

Orthorh. 
Page  205. 

3e(Be.OH)BO,. 

Grayish-white. 

Vitreous. 

C.  Piuac.  ,  per. 

7.5 

2.35 

Orthorh. 

AlF)a8iO4. 

)H  iso.  w.  F. 

Colorless, 
yellow,  pink, 
bluish, 
greenish. 

Vitreoug. 

C.  Basal,  per. 
F.  Uneven. 

8 

3.52- 
3.57 

Orthorh. 
Page  204. 

(Page  301.) 

II.  MINERALS   WITHOUT   METALLIC  LUSTER. 

C.— Infusible  or  Very  Difficultly  Fusiblec 

DIVISION  5. — Insoluble  in  hydrochloric  acid,  or  only  slightly  acted  upon. 

Section  b, — Hardness  equal  to  or  greater  than  that  of  glass. — Can  not  be  scratched  by 

knife.  — Continued. 


301 


II.   MINERALS   WITH01 

C.— Infusible  or  Ver 

DIVISION  5. — Insoluble  in  hydrocJiloric  ad 

Section  b. — Hardness  equal  to  or  greater  than  that  of 


General  Characters. 

Specific  Characters, 

Name  of  Species. 

Become  black  when  heated  B.  B.  , 
and  fuse  when  in  very  fine 
spliuters,  Fus.  =  6. 

Distinguished  by  differences  in  cleavage.  —  An- 
thophyllite  occurs  usually  in  slender  prisms 
and  is  often  fibrous. 

Anthophyllite. 

(Asbestus  in  part.) 

ENSTATITE. 

(Bronzite.) 

Becomes  slightly  magnetic  after  heating  B.  B. 

Hypersthene. 

Characterized  by  the  absence  of 
silica.  —  The  finely  powdered 
minerals  are  wholly  soluble  iu 
the  salt  of  phosphorus  bead 
(p.  112,  §  5),  and  when  made 
into  a  paste  with  cobalt  nitrate 
and  intensely  ignited  B.  B.  on 
charcoal,  assume  a  blue  color 
(aluminium). 

Characterized  by  extreme  hardness.  Frequently 
occurs  in  twin  crystals.  Alexandrite  is  a 
variety  which  appears  green  by  day,  and  red 
by  lamplight. 

Chrysoberyl. 

(Alexandrite.) 

Gives  water  in  the  closed  tube. 

Diaspore. 

Silicates.  —  The  finely  powdered 
minerals  are  decomposed  when 
fused  in  the  salt  of  phosphorus 
bead,    leaving    a    skeleton    of 
silica    (p.     112,   §  5).—  When 
made  into  a  paste  with  cobalt 
nitrate  and   intensely    ignited 
B.   B.    on  charcoal,  assume  a 
blue  color  (aluminium). 
JEir  Compare  Cyanite  (p.  302). 

In  the  closed  tube  at  a  red  heat  unchanged,  but 
on  intense  ignition  B.  B.  whitens  and  gives 
water.  The  color  given  by  cobalt  nitrate  is 
more  of  a  lavender  than  blue. 

Bertrandite. 

Occurs  in  fibrous  or  columnar  aggregates.  Con- 
tains magnesium  (p.  110,  §  4). 

Kornerupine. 
(Prismatine.) 

Occurs  usually  in  stout,  nearly  rectangular  prisms, 
with  carbonaceous  impurities  disposed  parallel 
to  the  axial  directions  of  the  crystals  (Chiasto- 
lite).  Often  impure  from  partial  alteration. 

ANDALUSITE. 

(Chiastolite.) 

Commonly  fibrous,  or  in  long  slender  crystals. 

SILLIMANITE. 

(Fibrolite.) 

Whitens  when  heated  in  the  closed  tube.  Gives 
the  reaction  for  boron  with  turmeric-paper  (p. 
56,  §2). 

Dumortierite. 

B.  B.  cracks,  whitens  and  fuses 
at  5|  to  a  white  enamel. 

In  the  closed  tube  at  a  red  heat  unchanged,  but 
on  intense  ignition  B.  B.  whitens  and  yields 
C  per  cent  of  water. 

Euclase. 

Gives  a  reaction  for  magnesium 
(p.  HO.  §  4). 

Usually  in  disseminated  grains. 

Sapphirine. 

In  the  closed  tube  at  a  high  tem- 
perature yields  water.  May 
become  slightly  magnetic  after 
heating  B.  B. 

Crystals  are  usually  tabular,  with  hexagonal  out- 
line. 
j 

Chloritoid. 

Ottrelite. 

DIVIBION  5,  Section  b. — Concluded  on  next  page. 


METALLIC   LUSTER. 
)ifficultly  Fusible. 

r  only  slightly  acted  upon. — Continued. 

s.— Can  not  be  scratched  by  a  knife.—  Continued. 


SOI 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard- 
ness. 

Specific 
Gravity. 

Crystalli- 
zation. 

g,Fe)SiO3. 
iso.  w.  Mg. 

Gray,      clove- 
brown,  green. 

Vitreous, 
pearly. 

C.  Prism.,  per. 

Angles    54°  & 
126°. 

5.5-6 

3.10 

Orthorh. 

g,Fe)SiO3. 

Gray,    brown, 
green. 

Pearly, 
bronze-like. 

C.  Prismatic. 
Angles    88°   & 
93°. 

5.5-6.5 

3.2-3.3 

Orthorh. 

g,Fe)SiO,. 

Browuish- 
green          to 
srreenish  -black 

Pearly. 

C.  Pioac.,  per. 
F.  Splintery. 

5-6 

3.3-3.5 

Orthorh. 

Ala04. 

Yellowish-, 
asparagus-     to 
emerald-green 

Vitreous. 

C.  Prismatic. 
F.  Uneven, 
conchoidal. 

8.5 

3.65-3.8 

Orthorh. 

0(OH). 

White,     gray, 
yellowish, 
greenish. 

Pearly, 
vitreous. 

C.  Pinac.,  per. 
F.  Couchoidal. 

6.5-7 

3.35- 
3.45 

Orthorh. 

2(Be.OH)3SiaO,. 

Colorless, 
white,  yellow. 

Pearly, 
vitreous. 

C.  Prismatic, 
basal,  and 
pinac.,  per. 

6-7 

2.59- 
2.60 

Orthorh. 
Hemimor. 

r(A10)2Si04. 

so.  w.  Mg. 

White   to   yel- 
lowish-brown. 

Vitreous. 

C.  Prismatic. 

6.5 

3.27- 
3.34 

Orthorh. 

3Si06. 

Flesh-red,  red- 
dish-brown, 
olive-green. 

Vitreous. 

C.  Prismatic. 
F.  Uneven. 

7.5 

3.16- 

3.20 

Orthorh. 

2SiO5. 

Hair-brown, 
gray,     gray- 
ish green. 

Vitreous. 

C.  Pinac.,  per. 
F.  Uneven. 

6-7 

3.23- 

3.24 

Orthorh. 

lO)6Al2(SiO4)3? 

so.  w.  Al. 

Deep-blue. 

Vitreous. 

0.  Pinacoidal. 
F.  Uneven. 

7. 

3.26- 
3.36 

Orthorh. 

!(A1.0H)SiO4. 

Colorless    to 
pale-green. 

Pearly, 
vitreous. 

C.  Pinac.,  per. 
F.  Couchoidal. 

7.5 

3.05-3.1 

Monocl. 

g5Al12Si2O27. 

Pale    blue    or 
green. 

Vitreous. 

F.  Uneven. 

7.5 

3.42- 
3.48 

Monocl. 

i(Fe,Mg)AlaSiO7. 

Dark        gray, 
green,  green- 
ish-black. 

Pearly, 
vitreous. 

C.  Basal,  per. 

6.5 

3.52- 
3.57 

Monocl. 

2(Fe,Mg,Mn)(Al,Fe)2 
Sia09. 

Greenish-gray, 
black. 

Vitreous. 

C.  Basal.  ,  per. 

6-7 

3.26 

Monocl. 

(Page  302.) 

II.  MINERALS   WITHOUT   METALLIC   LUSTER. 

C.— Infusible  or  Very  Difficultly  Fusible. 
DIVISION  5.— Insoluble  in  hydrochloric  acid,  or  only  slightly  acted  upon. 

Section  b. — Hardness  equal  to  or  greater  than  that  of  glass. — Can  not  be  scratched  by  a 

knife. — Concluded. 


302 


II.  MINERALS  W1THC 

C.— Infusible  or  Vc 

DIVISION  5.— Insoluble  in  hydrochloric  « 

iSeetion  b.  —Hardness  equal  to  or  greater  than  thai  < 


General  Characters. 

Specific  Characters. 

Name  of  Species 

Fuse  B.  B.  in  a  NaaCO3  bead  and  treat  with  1  cc.  HC1  and  1  cc.  of  water.    A  tur- 
meric-paper placed  in  this  solution  assumes  an  orange  color  (zirconium,  p.  133). 
Fusible  B.  B.  on  the  thinnest  edges. 

Baddeleyite. 

Characterized  by  distinct  cleav- 
ages in  two  directions  at  90°  or 
nearly  90°  to  one  another. 

Fusibility  5. 

THE  FELDSPARS 

See  Div.  5,  p.  282 

Usually    in    bladed    crystals.  — 
Readily  scratched  by  steel  in 
the  direction  parallel    to    the 
cleavage,  but  harder  than  steel 
at  right  angles  to  the  cleavage. 

Assumes  a  blue  color  when  moistened  with 
cobalt  nitrate  and  ignited  (aluminium). 

CYANITE. 

(Disthene.) 

After  fusion  with  Na2CO3  and  dissolving  in  HNO3  the  solution  gives  the  reaction 
for  a  phosphate  with  ammonium  molybdate  (p.  102,  §  1). 

Turquois. 
(Kallait.) 

Behave  like  quartz  (page    299) 
when  fused  with  NaaCO3  on 
platinum  wire. 

Anhydrous.  —  Structure  botryoidal,  stalactitic  or 
iu  crusting.  Carnelian  is  red,  Chrysoprase 
green. 

CHALCEDONY. 

(Carnelian,  Chryi 
prase.) 

Give  a  little  water  upon  intense  ignition  in  the 
closed  tube.  Hyalite  is  colorless  opal. 

OPAL. 

(Hyalite.) 

T  METALLIC  LUSTEK. 
Difficultly  Fusible. 
,  or  only  slightly  acted  upon. — Concluded. 
last.— Can  not  be  scratched  by  a  knife.— Concluded. 


302 


Composition. 

Color. 

Luster. 

Cleavage  and 
Fracture. 

Hard. 

ness. 

Specific 
Gravity. 

Crystalli- 
zation. 

SrOa. 

Colorless, 
yellow,  brown, 
black. 

Greasy, 
adamantine. 

C.  Basal.             6.5 

5.5         Monocl. 

Silicates  of 
U,K,  Na  &  Ca. 

White,  gray, 
yellow,  red. 

Vitreous. 

C.  Basal  &       1  « 
Pinacoidal.     ° 

2.55-      Monocl, 
2.80  Triclinio. 

kitSiO* 

Blue.  At  times 
white,  gray, 
or  green. 

Vitreous, 
pearly. 

C.  Pinacoidal, 
perfect. 

5-7 

3.56- 
3.66 

Triclinic. 
Page  217. 

3(A1.20H)3PO4. 

Cu.OH)'  iso.  w.  (A1.2OH)'. 

Blue,  bluish- 
green,  green. 

Wax-like. 

F.  Uneven.       ,  6 

2.6-2.8  Massive. 

510,. 

White,  gray, 
brown,  blue, 
red,  green. 

Wax-like. 

F.  Uneven, 
splintery. 

7 

2.6-2.64 

Massive. 

MOa  with  water. 

Colorless,  red, 
yellow,  green, 
blue,  gray. 

Vitreous, 
resinous. 

3\  Conchoidal. 

5.5-6.5 

2.1-2.2 

Amorph. 

INDEX  TO  SUBJECT-MATTER. 


Acids,  4 

Acid  sulphate  of  potash,  25 
Adamuntiiie  luster,  228 
Agate  mortar,  20 
Alcohol-lamp,  15 
Aluminium,  42 
Ammonia,  reagent,  28 
Ammonium,  43 
Ammonium  carbonate,  29 

hydroxide,  28 

molybdate,  29 

oxalate,  30 

sulphide,  29 

sulphocyanate,  30 

Amorphous  structure,  221 

Antimony,  43 

Anvil,  20 

Apparatus,  10 

Aqua  regia,  28 

Arsenic,  47 

Atomic  weight,  5 

Atoms,  3 

Axes,  crystallographic,  159 

Balances  for  specific  gravity,  234 
Barium,  52 
Barium  chloride,  30 

hydroxide,  28 

Base,  hexagonal  system,  187 

,  monoclinic  system,  210 

,  orthorhombic  system,  201 

,  tetragonal  system,  179 

,  tricliuic  system,  215 

Bases,  4 
Beakers,  21 
Beam  Balance,  235 
Beryllium,  53 
Bismuth,  54 
Blowing,  13 
Blowpipe,  10 
Blowpipe  flame,  33 

lamps,  14 

tips,  11 

Bone-asb,  26 
Borax,  24 

,  reactions  with,  148 

glass,  25 


Boron,  56 

Botryoidal  structure,  222 
Brachy-dome,  201,  215 
Brachy-pinacoid,  201,  215 
Bromine,  57 
Bulb  tubes,  18 
Buuseu  burner,  13 
flame,  31 

Cadmium,  57 
Caesium,  58 
Calcium,  58 
Caudle-flame,  31 
Carbon,  61 
Carbonates,  62 
Casseroles,  22 
Centimeter  scale,  41 
Cerium,  64 
Charcoal,  16 

,  reactions  on,  142 

,  uses  of,  39 

Chemical  affinity,  3 

analyses,  6 

composition,  calculation  of,  5 

equations,  5 

-  principles,  1 

Chemistry,  3 

Chlorine,  reactions  of,  67 

— ,  reagent,  27 
Chromium,  69 
Cleavage,  223 
Clino-dpme,  210 
Clino-piuacoid,  210 
Closed  tubes,  18 

,  reactions  in,  137 

Cobalt,  71 

Cobalt  nitrate,  reactions  with,  146 

,  reagent,  29 

Cohesion,  223 
Color,  228 

Columbium  (see  Nicobium),  98 
Columnar  structure,  221 
Combinations  of  crystal  forms,  166 
Combustion,  31 
Compact  structure,  221 
Cotiehoidal  fracture,  225 
Copper,  71 


304 


INDEX   TO   SUBJECT-MATTER. 


Crystal  combinations,  166 

form,  163 

habit,  165 

Crystallization,  155 

Cube,  170 

Cubic  centimeter,  41 

Decrepitation,  34 
Definite  proportion,  law  of,  3 
Deltoid  dodecahedron,  175 
Diamond  mortar,  19 
Didymium,  65 
Dimorphism,  8 
Diploid,  173 
Distorted  crystals,  165 
Dodecahedron,  170 
Domes,  mouoclinic,  210 

,  orthorhombic,  200 

,  triciiuic,  215 

Droppiug-bottle,  23 
Dropping-bulb,  23 

Earthy  structure,  221 
Elements,  3 
Erbium,  65 

Fibrous  structure,  221 
File,  20 
Filtering,  22 
Filter-paper,  21 
Flame  coloration,  35 

,  table  of,  136 

Flame,  nature  of,  31 
Fluorine,  75 
Foliated  structure,  221 
Forceps,  15 
Fracture,  225 
Fuel,  13 
Funnel,  21 

Fusibility,  scale  of,  230 
Fusion,  33 

Gadolinium,  65 

Gallium,  78 

Germanium,  78 

Glass  tubing,  17 

Globular  structure,  222 

Glowing,  231 

Glucinum  (see  Beryllium).  53 

Gold,  78 

Goniometers,  158 

Granular  structure,  221 

Greasy  luster,  228 

Gypsum  tablets,  17 

Habit  of  crystals,  165 
Hackly  fracture,  225 
Hammer,  20 
Hardness,  scale  of,  226 
Heavy  solutions,  236,  238 
Helium,  80 
Hemihedrism,  164 
Hemimorphism,  164 
Hexagonal-hombohedral  system,  191 


Hexngonal  system,  184 
Hexakistetrahedron,  175 
Hexoctahedron,  172 
Holders  for  platinum  wire,  16 
HololiL'drul  forms,  164 
Hydriodic  acid,  28 
Hydrocarbons,  61 
Hydrochloric  acid,  27 
Hydrochlorplatinic  acid,  28 
Hydrogen,  81 
Hydrogen,  sulphide,  27 
Hyilroxyl,  81 

Inch  scale,  41 
Indices,  161 
Indium,  82 
Iodine,  82 
Iridium,  104 
Iron,  83 

Isometric  system,  169 
Isomorphism,  7 
Ivory  spoon,  21,  41 

Jolly  Balance,  234 

Lamps,  13 
Lamp-stand,  23 
Lanthanum,  65 
Lead,  87 

Lead,  granulated,  26 
Leus,  20 
Lithium,  90 
Litmus-paper,  25 
Loops,  16 
Luster,  227 

Macro-dome,  201,  215 
Macro-piuacoid,  201,  215 
Magnesium,  91 
Magnesium  ribbon,  26 
Magnet,  20 
Malleable,  226 
Mammillnry  structure,  222 
Manganese,  92 
Massive  structure,  221 
Mathematical  ratio,  law  of,  160 
Mercury,  93 
Metallic  luster,  227 
Metal  scoop,  21 
Micaceous  structure,  221 
Mineral  kingdom,  1 
Minerals,  1 

,  determination  of,  239 

— ,  tables  for  determination,  245 
Molecular  weight,  5 
Molecules,  3 
Molybdenum,  95 
Monoclinic  system,  208 
Mortars,  19 
Mouthpiece,  12 

Neodymium,  65 
Nickel,  96 
Niobium,  98 


INDEX  TO   SUBJECT-MATTER. 


305 


Nitric  acid,  28 
Nitrogen,  99 

Nitrohydrochloric  acid,  28 
Non-metallic  luster,  228 
Normal  forms,  164 

Octahedron,  170 
Oil  for  fuel,  14 
Oil  of  vitriol,  28 
Oily  luster,  228 
Open  tubes,  18 

,  table  of  reactions,  140 

Organic  matter,  61 
Ortho-dome,  210 
Ortho-pitiacoid,  210 
Ortuorhombic  system,  199 
Osmium.  104 
Oxidation,  35 

,  with  nitric  acid,  120 

Oxide  of  copper,  26 
Oxidizing  flame,  36 
Oxygen,  100 

Palladium,  104 
Parameters,  160 
Parting,  224 
Pearly  luster,  228 
Pentagonal  dodecahedron,  173 
Phosphorescence,  231 
Phosphorus,  phosphoric  acid,  101 
Phosphorus  salt,  25 

,  table  of  reactions,  149 

Pinacoids,  hexagonal,  187 

,  monocliuic,  210 

,  orthorhombic,  20J  ! 

,  tetragonal,  179 

,  triclinic,  215 

Pipette,  23 
Platinum,  103 
Platinum  chloride,  28 

loops,  16 

pointed  forceps,  15 

spoon,  16 

wire,  16 

Pliers,  20 

Porcelain  crucibles,  22 

—  dishes,  22 
Potassium,  105 

bisulphate,  25 

bisulphate  and  fluorite,  26 

ferricyaulde,  30 

ferrocyanide,  30 

hydroxide,  28 

iodide  and  sulphur,  26 

mercuric  iodide  solution,  236 

• nitrate.  26 

pyrosulphate,  25 

Praseodymium,  05 
Precipitation,  30 
Prisms,  hexagonal,  187 

,  mouoclinic,  209 

,  orthorhombic,  200 

,  tetragonal,   179 

,  triclinic,  215 


Pseudomorphous  crystals,  218 
Pyramids,  hexagonal,  186 

,  mouocliuic,  209 

,  orthorhombic,  200 

,  tetragonal,  177 

,  tricliuic,  215 

Pyritohedrou,  173 
Pyroelectricity,  231 

Radiated  structure,  222 
Rare-earth  metals,  65 
Reagents,  24 

,  reactions  with,  151 

Reamer,  11 
Reducing  flame,  36 
Reduction,  36 
Reniform  structure,  222 
Resinous  luster,  228 
Rhodium,  104 
Rhombohedral  system,  191 
Rhoinbohedrons,  191 
Roasting,  39 
Rocks,  2 
Rubidium.  106 
Ruthenium,  104 

Salts,  4 

Samarium,  65 

Scale  of  hardness,  158 

Scalenohedron,  hexagonal,  192 

,  tetragonal,  184 

Scandium,  65 
Scoop,  21 
Selenium.  107 
Separatory  funnel,  238 
Silicon,  107 
Silky  luster,  228 
Silver,  113 
Silver  nitrate,  30 
Sodium,  115 
Sodium  carbonate,  24 

metaphosphate,  25 

,  table  of  reactions,  149 

phosphate,  30 

tetraborate,  24 

Spatula,  21 
Specific  gravity,  232 
Sphenoid,  orthorhombic,  208 

,  tetragonal,  183 

Splintery  fracture,  225 

Spring  Balance,  234 

Stalactitic  structure,  222 

Streak,  streak  plates,  228 

Strontium,  116 

Structure  of  minerals,  221 

Sub-metallic  luster,  227 

Sulphates,  122 

Sulphides,  118 

Sulphur,  118 

Sulphuric  acid,  28 

Symbols,  3 

Symmetry,  162 

Systems  of  crystallization,  169,  219 


306 


INDEX  TO   SUBJECT-MATTER. 


Tantalum,  123 
Tellurium,  124 
Tenacity,  226 
Terbium,  65 
Test-paper,  25 
Test-tube,  21 
Test-tube  holder,  21 
Test-tube  stand,  21 
Tetragonal  system,  177 
Tetrahedron,  175 
Tetrahexahedron,  172 
Thallium,  125 
'  Thorium,  65 
Thulium,  65 
Tin,  125 

,  granulated,  26 

Titanium,  127 
Trapezohedron,  hexagonal,  197 

,  isometric,  171 

Triclinic  system,  214 
Trisoctahedron,  172 
Tristetrahedron,  175 
Trimorphism,  8 
Truncations,  167 
Tungsten,  128 


Turmeric-paper,  25 
Twin  crystals,  167 

Uneven  fracture,  225 
Uranium,  129 

Valence,  4 
Vanadium,  130 
Vitreous  luster,  228 

Watch-glasses,  21 
Water,  reagent,  27 

,  test  for,  81 

Water  of  crystallization,  81 
Wash-bottle,  23 
Washing.  22 
Westphal  Balance,  236 

Ytterbium,  65 
Yttrium,  65 

Zinc,  130 

,  granulated,  26 

Zirconium,  133 


INDEX  TO  MINERALS. 


Aanerodite,  254 
Acanthite,  251 
Achroite,  300 
Acraite,  270 
Actinolite,  288 
Adamite,  275 
Adelite,  275 
^Egirite,  270 
^Enigmatite,  270 
JSscbyuite,  300 
Agalraatolite,  296 
Agate,  299 
Agricolite,  262 
Aguilarite,  248 
Aikinite,  251 
Alabandite,  253 
Alabaster,  274 
Albite,  285 
Alexandrite,  301 
Algodonite,  246 
Allactite,  275,  292 
Allanite,  254,  269,  280 
Allemontite,  246 
Alloolasite,  246 
Allophaue,  294 
Almandite,  270 
Altaite,  248 
Alumian,  291 
Ahnninite,  291 
Aluminium  Ore,  297 
Alunite,  290,  296 
Aluuogen,  291 
Alurgite,  284 
Amalgam,  253 
Amarantite,  267 
Amblygonite,  283 
Amesite,  296 
Amethyst,  !<J99 
Ammonia  Alum,  291 
Amphibole,  288 
Analcite,  282 
Anatase,  299 
Audalusite,  301 
Andesite,  285 
Andorite,  249 
Andradite,  269 


Anglesite,  260 
Aubydrite,  274 
Ankerite,  289 
Annabergite,  267 
Auortbite,  280,  285 
Anortboclase,  285 
Antbopbyllite,  287,  301 
Antimony,  249 
Antimony  Glance,  249 
Apatite,  276,  293 
Apbtbitalite,  272 
Apjobuite,  291 
Apopbyllite,  282 
Aquamarine,  287,  300 
Aragonite,  289 
Ardennite,  286 
Arfvedsouite,  270 
Argentite,  251 
Argyrodite,  253 
Arsenic,  246 
Arseuiosiderite,  267 
Arsenolite,  258 
Arseuopyrite,  247 
Asbestus,  autbopbyllite,287, 
301 

,  serpentine,  281,  295 

,  tremolite,  288 

Asbolite,  292 
Astropbyllite,  269 
Atacamite,  263 
Atelestite,  262 
Atopite,  298 
Augelite,  293,  296 
Augite,  288 
Auricbalcite,  290 
Automolite,  298 
Autuuite,  276 
Awaruite,  255 
Axinite,  285 
Azurite,  263 

Babingtonite,  270,  288 
Baddeleyite,  302 
Barite,  274 

Barium  Feldspar,  285 
Barrandite,  268 


Barysilite,  262 
Barytocalcite,  289 
Bastnasite,  297 
Bauxite,  297 
Bayldonite,  260 
Bechilite,  277 
Beegerite,  251 
Belonesite,  277 
Bementite,  281 
Berauuite,  268 
Bertbierite,  250 
Bertrandite,  301 
Beryl,  287,  300 
Beryllonite,  27? 
Berzelianite,  24.7 
Berzeliite,  275 
Beudantite,  260 
Bieberite,  291 
Bindbeimite,  261 
Binnite,  246 
Biotite,  269,  270,  284 
Bismutb,  253 
Bismutb  Glance,  251 
Bismuthinite,  251 
Bismutite,  262 
Bismutosmaltite,  246 
Bismutosphaerite,  262 
Bixbyite,  253 
Black  Jack,  252 
Black  Lead,  256 
Blende,  Zinc  Blende, 
Blodite,  272 
Blue  Vitriol,  264 
Bobierrite,  277 
Bog  Iron  Ore,  292 
Bog  Manganese,  292 
Boleite,  261 
Boracic  Acid,  277 
Boracite,  277 
Borax,  273,  277 
Borickite,  268 
Bornite,  252 
Botryogeu,  266 
Boulangerite,  249 
Bournonite,  249 
Boussingaultite,  272 
307 


308 


INDEX   TO   MINERALS. 


Brackelmschite,  260 
Brandtite,  275 
Bnmuite,  254,  256 
Breithauptite,  250 
Breunuerite,  289,  290 
Brewsterite,  282 
Brochantite,  264 
Broinlite,  289 
Bromyrite,  259 
Brongniardite,  249 
Bronzite.  287,301 
Brookite,  300 
Brown  Hematite,  266,  292 
Brucite,  290,  293 
Brushite,  276 
Bunsenite,  292 

Cabrerite,  267 
Cacoxeuite,  268 
Calamine,  278,  294. 
Calaverite,  248 
Calcioferrite,  268 
Calciovolborthite,  265 
Calcite,  289 
Caledonite,  260 
Callaiuite,  293 
Calomel,  258 
Cancriuite,  278 
Canfieldite,  253 
Cappelenite,  279 
Caracolite,  260 
Carbonado,  298 
Carminite,  260 
Carnallite,  271 
Carnelian,  302 
Carpbolite,  286 
Carphosiderite,  267 
Carrol  lite   252 
Caryinite,  260 
Caryoceriie,  295 
Cassiteiite,  299 
Castanite,  267 
Catapleiite,  281 
Celestite,  274 
Cenosite,  278 
Cera  rgy  rite,  259 
Cerite/294 
Cemssite,  259 
Cervantite,  297 
Cbabazite,  282 
Chalcanthite,  264 
Chalcedony,  302 
Chalcocite,  252 
Chalcodite,  269 
Chalcomenite.  265 
Chalcopbanite,  256 
Cbalcophyllite,  265 
Chalcopyrite,  252 
Chalcosiderite,  265,  268 
Chalcostibite,  250 
Chenevixite,  264 
Chert,  299 
Chiastolite,  301 
Childrenite,  268 


Chiolite,  274 
Chiviatite,  251 
Chloanthite,  247 
Chlorite,  284,  296 
Chloritoid,  301 
Chloropal,  295 
Choudrodite,  294 
Chrome    Clinochlore,    284, 
296 

Garnet,  299 

Mica,  284 

Chromic  Iron,  256 
Chromite,  256,  298 
Chrysoberyl,  301 
Chrysocolla,  295 
Chrysolite,  294 
Chrysoprase,  302 
Chrysotile,  281,  295 
Churchite,  293 
Cimolite,  297 
Cinnabar,  258 
Cirrolite,  276.  283 
Claudeiite,  258 
Clausthalite,  248 
Clinochlore,  284,  296 
Clinobediite,  278 
Clinocksite,  264 
CHnohumite,  294 
Clinozoisite.  287 
Clintonite,  296 
Cobalt  Bloom,  267 
Cobaltite,  246 
Colemanite,  277 
Collophanite,  276 
Collyrite,  297 
Coloradoite,  248 
Columbite,  254.  257 
Comptonite,  278 
Conichalcite.  264 
Connellite,  263 
Cookeite,  284 
Copiapite,  267 
Copper,  253 

Glance,  252 

Nickel,  247 

Pyrites,  252 

Copperas,  266 
Coquimbite,  266 
Cordierite,  287,  300 
Cornwallite,  265 
Corundophilite,  296 
Corundum,  299 
Corynite,  247 
Cosalite,  251 
Cotu unite,  258,  261 
Covellite,  252 
Crednerite,  256 
Crocidolite,  270 
Crocoite,  261 
Cronstedtite,  269 
Crookesite,  247 
Cryolite,  274 
Cubanite,  252 
Cuinengite,  261 


Cuprite.  254,  263 
Cuprobismutite,  251 
Cuprodescloizite,  26? 
Cuproiodargyrite,  25£ 
Cuprotungstite,  265 
Cyanite,  302 
Cyanochroite,  264' 
Cyanotrichite,  264 
Cylindrite,  249 
Cyprusite,  267 

Dahliite,  290 
Daualite,  269,  294 
Danburite,  285 
Darapskite,  272 
Datolite.  278 
Daubreelite,  262 
Daubreeite,  255 
Dawsonite,  273,  289 
Derbylite,  255 
Descloizite,  .260 
Desmine,  282 
Deweylite,  281,  295 
Diadochite,  266 
Diallogite,  290 
Diamond,  298 
Diaphorite,  249 
Diaspore,  301 
Dicldnsouite,  276 
Dietrichite,  291 
Dietzeite,  274 
Dihydrite,  265 
Diopside,  288 
Dioptase,  294 
Disluite,  298 
Disthene,  302 
Dolerophanite,  264 
Dolomite,  289 
Domeykite,  246 
Dry-bone  Ore,  290 
Dufrenite,  268 
Dufrenoysite,  246 
Dumortierite,  301 
Durangite,  275 
Durdenite,  268 
Dysanalyte,  257 
Dyscrasite,  250 

Ecdemite,  260 
Edingtonite.  278 
Elseolite,  280 
Electrum,  253 
Eleonorite,  268 
Embolite,  259 
Emerald,  287,  300 
Emerald  Nickel,  290 
Emery,  299 
Emplectite.  251 
Enargite,  246 
Endlichite,  260 
Enstatite,  287,  301 
Eosphorite,  276 
Epiboulangerite,  249 


INDEX   TO   MINERALS. 


309 


Epididymite,  287 
Epidote,  287 
Epigenite,  246 
Epistilbite,  282 
Epsomite,  Epsom  Salt,  272 
Erinite,  265 
Erythrite,  267 
Ettringite,  274 
Eucairite,  247 
Euchroite,  265 
Euclase,  288,  301 
Eucolite,  279 
Eudialyte,  279 
End idy mite,  288 
Eulyti'te,  262 
Euxenite,  300 
Evansite,  293 

Fairfieldite,  276 
Falkeubaynite,  250 
Famatiuite,  250 
Faujasite,  282 
Fayalite,  269 
Feather  Ore,  249 
Feldspar,  285 
Fels5banyite,  291 
Fergusonite,  299 
Ferronatrite,  266 
Fibroferrite,  267 
Fibrolite,  301 
Fillowite,  276 
Fisoherite,  293 
Flinkite,  275 
Flint,  299 
Fluellite,  297 
Fluocerite,  293 
Fluorite,  274 
Fluor  Spar,  274 
Footeite,  263 
Forbesite,  267 
Forsterite,  294 
Fowlerite,  286 
Franckeite,  249 
Fraukliuite,  255 
Freibergite,  250 
Freieslebenite,  249 
Friedelite,  281 
Fuehsite,  284 

Gadolinlte,  280,  294 
Gahnite,  298 
Galena,  251 
Galenobismutite,  251 
Ganomalite,  262 
Ganophyllite,  278 
Garnet,  287 

Almandite,  270 

Andradite,  269 

Grossularite,  287 

Pyrope,  287 

Spessartite,  286 

Uv;irovito,  299 

Garnierile,  295,  297 
Gay-Lussite,  273 


Gearksutite,  274 
Gehlenite,  280,  294 
Geikielite,  257 
Genthite,  295,  297 
Geocronite,  249 
Gerlmrdtite,  264 
Gersdorffite,  247 
Gibbsite.  293,  297 
Gismondite,  278 
Glauberite,  274 
Glauber  Salt,  272 
Glaucodot,  246 
Glaucophane,  288 
Glockerite,  267 
Gmeleuite,  282 
Goethite,  266,  292 
Gold.  253 
Goslarite,  291 
Gothite,  266,  292 
Goyazite,  296 
Graphite,  256 
Gray  Copper,  250 
Greenockite,  292 
Grossularite,  287 
Grunlingite,  248 
Guanajuatite,  248 
Guarinite,  286 
Guitermanite,  246 
Gummite,  293 
Gymnite,  281,  295 
Gypsum,  274 
Gyrolite,  278 

Haidingerite,  275 
Halite,  271 
Halloysite,  297 
Halotrichite,  266 
Hambergite,  300 
Hamlinite,283 
Hauksile,  271 
Harmotome,  282,  286 
Hatchettolite,  298 
Hauchecornite,  250 
Hnuerite,  253 
Hausrnannite,  256 
Hautefeuillite,  277 
Haiiyne,  279 
Haiiynite,  279 
Heavy  Spar,  274 
Hedenbergite,  288 
Heintzite,  277 
Helvite,  279 
Hemafibrite.  275 
Hematite,  255,  292 
Hematolite,  292 
Hemimorphite,  294 
Hercynite,  298 
Herderite,  276,  283 
Herrengrundite,  264 
Hessite7  248 
Heulaudite,  282 
Hiddenite,  285 
Hielrnite,  257 
Hiortdahlite,  280 


Hisingerite,  295 
Hceruesite,  275 
Homilite,  279 
Hopeite,  277 
Horn  Silver,  259 
Hornblende,  288 
Hortonolite,  269 
How  lite,  285 
Htibnerite,  283 
Huebnerile,  285 
Humite,  294 
Hureaulite,  276 
Hyacinth,  299 
Hyalite,  302 
Hyalophane,  285 
Hyalotekite,  262 
Hydrargillite,  297 
Hydroboracite,  277 
Hydrocerussite,  259 
Hydrocynnite,  264 
Hydrogioberite,  289 
Hydro- hematite,  255,  292 
Hydro-herderite,  276,  283 
Hydromagnesile,  239 
Hydronepbelite,  278 
Hydrophilite,  271 
Hydrotalcite,  293 
Hydroziucite,  290 
Hypersthene,  270,  301 

Idocrase,  287 
Ihleite,  266 
Ilesite,  291 
Ilmenite,  255,  257 
Ilvaite,  254,  269 
Inesite.  281 
Indicolite,  300 
lodobromite,  259 
lodyrite,  259 
lolite,  287,  300 
Indium,  257 
Iiidosmine,  257 
Iron,  255 

Iron  Chrysolite,  269 
Iron  Pyrites,  252 
Isoclasite,  276 

Jacobsite,  255 
Jade,  288 
Jadeite,  288 
Jamesonite,  249 
Jarosite,  266 
Jasper,  299 
Jefferisite,  281 
Jeffersonite,  286 
Jeremejevite,  300 
Johannite,  291 
Jordanite,  246 

Kainite.  271 
Kainosite,  278 
KaiseriU ,  272 
Kalinite,  272,  290,  291 
Kallaite,  302 


310 


INDEX   TO    MINERALS. 


Kallilite,  250 

Loweite.  272 

Miersite,  259 

Kftmmererite,  284,  296 

LSwigite,  291,  296 

Milarite,  287 

Kaoliuite,  297 

Lougbauile,  254 

Millerite,  252 

Keilhanite,  286 

Loraudite,  258 

Mimetite,  260 

Kentrolite,  254,  262 

Losseoite,  260,  267 

Miuervite,  293 

Kermesite.  258 

Ludlamite,  268 

Minium,  262 

Kieserite,  272 

Ludwigite,  268 

Mirabilite,  272 

Kilbrickenite,  249 

Luneburgite,  277 

Misenite,  272 

Klaprotholite,  251 

Mispickel,  247 

Knebelite,  269 

Mairnesian-chromite,  256 

Mixite,  264 

Knoxvillite,  266 

Magnesioferrite,  255 

Molybdenite,  256 

Kobellite,  249 

Magnesite,  289,  290 

Mouazite,  296 

Koninckite,  268 

Magnetic  Iron,  253 

Moueiite,  276 

Kornerupine,  301 

Magnetic  Pyrites,  252 

Moutanite,  262 

Kottigite,  275 

Magnetite,  253,  255 

Montebrasite,  283 

Kreuuerite,  248 

;Malacbite,  263 

Monticellite,  280 

Krohnkite,  264 

Mallardite,  291 

Montmorilliuite,  297 

Kylindrite,  249 

Manganese  Amphibole,  286 

Mordenite,  286 

'  Epidote,  286 

Morenosite,  291 

Laaugbanite,  254 

Garnet,  286 

Mosaudrite,  281 

Labradorite,  285 

Pyroxene,  286 

Mossite,  257 

Lauarkite,  260 

Mangauite,  256 

Muscovite,  284 

Langbeinite,  272 

Maugano-columbite,  298 

Ltuigite,  264 

Mangauosite.^  292 

Nadorite,  261 

Lansfordite,  289 

Manganostibite,  292 

Nagyagite,  248    | 

Laois-Lazuli,  279 

Mangano-tantalite,  298 

Nantokite,  263 

Larkinite,  275 

Marble,  289 

Natrolite,  278 

Laumontite,  278 

Marcasite,  252 

Natron,  271 

Laurionite,  26  L 

Margarite,  284 

Natrophilite,  276 

Laurite,  257 

Marialite,  287 

Nan  maun  ite,  248 

Lautarite,  274 

Marmolite,  281,  295 

Nepheline,  280 

Lautite,  246 

Marshite,  263 

Nepbelite,  280 

Lawsonite,  287 

Martiuite,  293 

Nephrite,  288 

Laxmanuite,  260 

Mascagnite,  258 

Neptunite,  254,  286 

Lazulite,  296 

Massicot,  262 

Nesquehouite,  289 

Lazurite,  279 

Mat  i  Id  lie,  251 

Newtonite,  297 

Lead,  253 

Matlockite,  261 

Niccolite,  247 

Leadhillite,  259 

Mauzeliite,  263 

Nickel  Bloom,  267 

Lecontite,  272 

Mazapilite,  267 

Niter,  273 

Lehrbachite,  247 

Meerschaum,  281,  295 

Nitrobarite,  273 

Lepidolite,  284 

Meionite,  283 

Nordeuskioldine,  300 

Lepidoinelane,  269 

Melaconite,  254 

Northupite,  273 

Lettsouiite.  264 

M«lanite,  280 

Noseau,  Noselite,  279 

Leucite,  295 

Melanocerite,  295 

Leucocbalcite,  265 

Melauophlogite,  299 

Ochrolite,  261 

Leucophamte,  287 

Melanoslibian,  255 

Octahedrite,  299 

Leucopyrite,  247 

Melanotekite,  253,  262 

Offretite,  286 

Levynite,  278 

Melanterite,  266 

Okenite,  278 

Lewisite,  263 

Melilite,  280 

Oldhiimite,  290 

Libetbenite,  265 

Melonile,  248 

Oligoclase,  285 

Liebigite,  289 

Mendipite,  261 

Olivenite.  265 

Lievrite,  254,  269 

Mendozite,  272 

Olivine,  294 

Lillianite,  251 

Meneghiuite,  249 

Onuerodite,  254 

Lime  Feldspar,  285 

Mucurial  Tetrabedrite,  250 

O  no  f  rite,  247 

Limestone,  289 

Murcury,  253 

Opal,  302 

Limonite,  266,  292 

Mesolite,  278 

Onuigite,  294 

Linarite,  260 

Metacinnabarile,  253 

Orpiment,  258 

LindackerUe,  264 

Metavoltaite,  266 

Ortboclase,  285 

Linnseite,  252 

Meteoric  Iron,  255 

GUI-elite,  301 

Liroconitc,  264 

Miargyrite,  250 

Litbia  Mica,  284 

Mica,  284 

Pachnolite,  274 

Lithiophilite,  276 

Microcline.  285 

Palladium,  257 

Livingston  ite,  249 

Microlite,  298 

Paragon  ite,  284 

Lollingite,  247 

Microsommite,  279 

Paramel  aconite,  254 

INDEX   TO    MINERALS. 


311 


Parisite,  290 
Partschinite,  286 
Peacock  Ore,  252 
Pearceite,  246 
Pearl  Spar,  289 
Pectolite,  282 
Peganite,  293 
Penfieldite,  261 
Penniuite,  284,  296 
Pentlandite,  252 
Percylite,  261 
Periclase,  293 
Peridot,  294 
Perovskite,  257,  297 
Petalite,  285 
Petzite,  248 
Phacolite,  282 
Pharmacolite,  275 
Pharmacosiderite,  267 
Phenucite,  300 
Phillipsite,  282 
Phlogopite,  284 
Phoeuicochroite,  261 
Phosgenite,  259 
Phosphosiderite,  268 
Phospburanylite,  276 
Picroinerite,  272 
Piedin6ntite,  286 
Pinakiolite,  277 
Pinnoite,  277 
Pirssonite,  273 
Pisanite,  264 
Pitch  Blende,  257 
Pitticite,  267 
Plagionite,  249 
Platinum,  257 
Plattnerite,  254,  262 
Plumbogummite,  260 
Polianite,  256 
Pol  Incite,  295 
I  Polyargyrite,  250 
Polybnsite,  250 
Polycrase,  300 
Polydyniite,  252 
Polyluilite,  274 
Polymignite,  257 
Porcelain  Clay,  297 
Potash  Alum,  272,  290,  291 
Potash  Mica,  284 
Potash  Feldspar,  285 
Powellite,  277 
Prehuite,  288,  287 
Prismatine,  301 
Prochlorite,  296 
Prolectite,  294 
Prosopite,  290,  297 
Prousiiie,  259 
Pseudobrookite,  255,  257 
Pseudomalachite,  265 
Psilomelane,  256 
Psittadnite,  260 
Ptilolite.  286 
Pucherite,  202 
Pyrargyrite,  250,  259 


Pyrite,  252 
Pyroaurite,  292 
Pyrochlore,  298 
Pyrochroite,  292 
Pyrolusite,  256 
Pyromorphile,  260 
Pyrope,  287 
Pyrophanite,  256 
Pyrophyllite,  296 
Pyrosmulite,  ~69 
Pyrostilpuite,  259 
Pyroxene,  288 
Pyrrhotite,  252 

Quartz,  299 
Quenstedtite,  266 

Raimondite,  267 
Ralstonite,  297 
Rammelsbergite,  247 
Raspite,  261 
Realgar,  258 
Reddingite,  276 
Red  Ziuc  Ore,  292 
Reiuite,  254 
Remingtonite,  290 
Rezybanyite,  251 
Rhabdophanite,  293 
Rhagite.  262 
Rhodizite,  277 
Rhodochrosite,  290 
Rhodonite,  286 
Richterits,  286 
Riebeckite,  270 
Riii kite,  280 
Ripidolite,  284,  296 
Rock  Crystal,  299 
Roeblingite,  262 
Rospperite,  269 
Romeite,  263 
Romerite,  266 
Roscoelite,  284 
Roseliie,  275 
Rubellite.  300 
Ruby,  299 

Copper,  263 

Silver,  259 

Spinel,  298 

Rutile,  299 

Safflorite,  246 
Sal-ammoniac,  258 
Sal-soda.  271 
Suit,  Common,  271 
Salt  of  Phosphorus,  277 
Samarskite,  254 
Sanidine,  285 
Sapphire,  299 
Sapphinne,  301 
Sarcolite,  280 
Sartorite,  246 
Sassolite,  277 
Scapolite,  283,  287 
Schapbachite,  251 


Scheelite,  283,  298 
Schefferite,  286 
Schirmerite,  251 
Schorlomite,  280 
Schrottcrite,  297 
Schwartzenbergite,  261 
Schwatzite,  250 
Scolecite,  278 
Scored ite,  267 
Scovillite,  293 
Selen-tellurium,  247 
Sellaite,  283 
Semseyite,  249 
Senarmontite,  258 
Sepiolite,  281,  295 
Serpentine,  281,  295 
Seybertite,  296 
Siderite,  266,  290 
Sideronatrite,  266 
Sillimauite,  301 
Silver,  253 

Silver  Tetrahedrite,  250 
Sipylite,  299 
Skutterudite,  246 
Smaltite,  246 
Smithsonite,  290 
Soapstone,  284,  296 
Soda  Feldspar,  285 
Soda  Mica,  284 
Soda  Niter,  273 
Sodalite,  279 
Spadaite,  278 
Spangolite,  263 
Spathic  Iron,  266,  290 
Specular  Iron,  255 
Sperrylite,  247 
Spessartite,  286 
Sphserite,  293 
Sphserocobaltite,  290 
Sphalerite,  252,  292 
Sphene,  283,  286 
Soinel,  298 
Spodumene,  285 
Stannite,  252 
Staurolite,  300 
Steatite,  296 
Siephanite,  250 
Stercorite,  277 
Sternbergite,  252 
Stibiconite,  297 
Stibiotautalite,  297 
Stibnite,  249 
Stilbite,  282 
Stilpnomelane,  269 
Stolzite,  261 
Strengite,  268 
Stromeyerite,  252 
Stroutianite,  289 
Struvite,  277 
Stylotypite,  250 
Sulphohalite,  271 
Sulphur,  258 
Sussexite,  277 
Svabite,  275 


312 


INDEX   TO   MINERALS. 


Svanbergite,  296 
Sychuodyinite,  252 
Sylvauite,  24b 
Sylvite,  271 
Symplesite,  2£2 
Synadelpliite,  £75 
Syngenite,  272,  274 
Szaibelyite,  277 
Szinikite,  291 

Tachydrite,  271 
Tagilite,  265 
Talc,  284,  296 
Tantalite,  257 
Tupalpite,  248 
Tapiolite,  257 
Tavistockite,  296 
Taylorite,  272 
Tellurium,  248 
Teunantite,  246 
Tenorite,  254 
Tephroite,  279 
Tetradymite,  248 
Tetrahedrite,  250 
Thaumasite,  273,  289 
Theiiardite,  272 
Thermonatrite,  271 
Thornsenolite,  274 
Thomson  ite,  278 
Thorite,  294 
Thuringite,  269 
Tiemannite,  247 
Tilasite,  275 
Tin,  253 
Tin  Pyrites,  252 
Tin  Stone,  299 
Titanic  Iron,  255 
Titanite,  283,  286 
Topaz,  300 
Torbernite,  265 
Tourmaline,  285,  300 
Tremolite,  288 
Trichalcite,  265 
Tridymite,  299 
Trimerite,  283 


Triphylite.  268 
Tripiite,  268 
Tiiploidite,  268 
Tripuhyite,  263,  297 
T  r5ge  rite,  275 
Troilite,  252 
Troim,  271 
Troostite,  279 
Tscheffkinite,  280 
Tschermigite,  291 
Tungstite,  298 
Turfite.  255,  292 
Turingite,  269 
Turquois,  302 
Tyrolite,  264 
Tysonite,  297 

Ulexite,  277 
Ullmannite,  250 
Umangite,  247 
Uraninite,  257 
TJran  Mica,  265 
Uranocircite,  276 
Uranophane,  294 
Uranopiljte.,  291 
Uranospinite,  275 
Uranothallite,  289 
Utahite,  267 
Uvarovite,  299 

Valentinite,  258 
Vauadinite,  260 
Variegated  Copper,  252 
Variscite,  296 
Vauquelinite,  260 
Vertniculite,  281 
Vesuviauite,  287 
Veszelyite,  264 
Vivianite,  268 
Volborthite,  265 
Voltaite,  266 
Voltzite,  293 

Wad,  293 


Wagnerite,  277 
Waipurgite,  262 
Warren  ite,  249 
Warwickite,  257,  297 
Wattevillite,  274 
Wavel lite,  296 
Wellsite.  282 
Wernerite,  283,  287 
Whewellite,  290 
White  Iron  Pyrites,  253 
Whitueyite,  246 
Willemite,  294 
Witherite,  273 
Wittichenite,  251 
Wohlerite,  280 
Wolfuchite,  247 
Wolframite,  254,  270 
Wolfsbergite,  250 
Wollastouite,  283 
Wulfenite,  261 
Wurtziie,  292 

Xanthoconite,  259 
Xauthophyllite,  296 
Xanthosid'erite,  266,  292 
Xenotime,  296 

Yttrocerite,  293 

Zaratite,  290 
Zepharovicbite,  293 
Zeunerite,  264 
Zioc,  253 

Zinc  Blende,  252,  293 
Zinc  Spinel,  298 
Zincaluminite,  291 
Zincite,  292 
Zi uken ite,  249 
Zinnwaldite,  270,  284 
Zircon,  299 
Zirkelite,  297 
Zoisite,  287 
Zorgite,  247 
Zunyite,  299 


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